2018 Updated Senate Predictions

Disclaimer: Predictions and ratings given here are my own. While they were determined after an analysis of all data, they are not confident predictors of the outcome of a race. Every race mentioned here has the opportunity to go either way. 

Here are my updated 2018 Senate predictions. Since my last prediction, many new polls have come out in the states of Missouri, Tennessee, Florida, Texas, and Arizona. Noteworthy events since the last prediction include the Missouri Governor’s scandal, Florida Governor Rick Scott announcing his candidacy, and outgoing Senator Bob Corker announcing that he will not campaign against Democrat Phil Bredesen. With that said, here’s my competitive tossup map. I’ll be discussing each seat individually, or you can skip to my final map.


Nevada provides a rare flip opportunity for Democrats this year: an unpopular incumbent in a Clinton state. In fact, this is the only Republican seat up in a Clinton state, compared to 10 Trump-state Democrats. However, this is still not a sure thing for Democrats. Nevada is historically a competitive state, and just because it swung one way for Clinton doesn’t mean it’ll swing the same way for Jacky Rosen, the Democrat running. Basing my prediction off of my previous post‘s methodology, I looked at multiple factors before categorizing this race, even if it did look like an easy pickup. For starters, we only have one poll for the race since the start of 2018. It gives the Democrat a 5-point lead, but it was conducted by PPP, a Democratic pollster.

Second, we have to look at the candidates. Jacky Rosen has served in the US House from Nevada, while Dean Heller, the incumbent, has been criticized for both his moderation and, later, his reversion to conservatism, angering both groups of the Republican party.

Finally, I looked at results for every Presidential election in Nevada since 2000, and what I found was that, while Nevada did swing to the Democrats by a 10-point margin when Obama first ran, the state has been trending closer to a pure tossup. While the trend towards Republicans since 2008 is noticeable, I think it is a reversion to the mean rather than a reversion to the Republicans. Using all of this information, and considering that this is a midterm and will not have the same turnout nor enthusiasm gap as a Presidential election, I can characterize Nevada as leaning blue this cycle, making it a flip for the Democrats.


Note: This was written before the AZ-08 special election took place. In my opinion, the swing seen in AZ-08 strengthens my rating. 

Arizona is a new swing state, going for Trump by only 3.5% in 2016. That margin is closer than Ohio, Iowa, and Colorado, all considered swing states. With the average swing seen in special elections, the Arizona Senate race will surely be competitive. Unlike in Nevada, there is no incumbent in this race. Jeff Flake announced last year that he would be retiring from the Senate, opening up the seat as a potential Democrat gain. In Presidential elections since 2000, Arizona has swung towards both parties, but always stayed within about 10%. In 2018, with a Democratic enthusiasm gap and an increased minority turnout, Arizona could flip.

The last thing to consider is the polls. The problem is, we don’t yet know the Republican incumbent. Martha McSally, Kelli Ward, and Joe Arpaio are all running for the nomination. Polls suggest that McSally, the more moderate of the group, is favored to win, though we don’t yet know given the difference in primary voters and general election voters. Kristen Sinema, on the other hand, is sure to win the nomination. She could be considered a conservative Democrat, and she voted against Nancy Pelosi while in the House. Assuming McSally does win the primary, Sinema is favored by 5.5 points in polls since 2018. Such as in Nevada, these polls were conducted by a Democratic pollster, but they can still be insightful. If another candidate wins the primary, Sinema is favored by an even greater margin. Taking all of these points into consideration, I’m rating Arizona as a leaning blue seat, bringing the flip count to 2.


Montana was once a swing state. In 2008, it was determined by only 11,000 votes. However, it has since trended Republican and wasn’t even considered competitive in 2016. That said, Montana has a Democratic Governor and an incumbent Democratic Senator. Jon Tester, the incumbent, is a conservative Democrat, voting with Trump about 38% of the time. This is a large percent, compared to some Senators like Elizabeth Warren voting with Trump only 8% of the time. Tester is very popular in his state, and the state has proven that it’s not scared of electing Democrats. In the 2017 special House election, Montana elected their next Representative by just 6%, despite the Democrat running being a progressive Bernie supporter. If Montana is willing to get 6% away from electing a progressive, I think they will easily re-elect a moderate.

In terms of polling, we only have a single poll, and it was conducted using a “Generic Republican,” rather than a specific candidate. “Generic” candidates always get more support than an actual candidate. When a respondent chooses between two “generics,” they tend to see the generic as identifying with their faction of the party. For example, a Tea Party voter might associate a generic Republican with a Tea Party Republican. Actual candidates are always flawed to at least one group, and almost perform worse than polls would suggest. With that said, the single poll showed Tester losing by 13% to a generic Republican. This data shouldn’t be pushed aside just because it doesn’t include a candidate, but it also shouldn’t be over-hyped. I rate Montana as leaning blue.

North Dakota

North Dakota could be the closest race in 2018, save Missouri or Florida. If I could, I’d rate this as a pure tossup, but I’m trying to rate every race, so I have to pick a side. We have a lot to look at before we can confidently determine a favorite.

First, let’s look at the candidates. Heidi Heitkamp, the Democratic incumbent, is a conservative. She votes with Trump 55% of the time, and Trump even asked her to switch to the Republican party. She didn’t, but she often breaks with the Democrats on major votes, such as the Pompeo nomination. The Republican, Kevin Cramer, originally said he wasn’t running, but later changed his mind. He currently serves as the statewide House Representative from North Dakota, meaning the voters are comfortable electing him statewide. Both candidates are strong, but only one is a Senate incumbent.

Next, let’s look at the voting trends of the state. Like Montana, North Dakota used to be competitive, and almost went for Obama in ’08. However, it’s since trended Republican, and went for Trump by over 30%. That said, the state has a history of electing Democrats to Congress, at one point having 2 Democratic Senators and a Democratic Representative. When voters go to the polls, they won’t vote against Heitkamp just because she’s a Democrat. Heitkamp has a net 8-point approval rating, meaning that voters think of her based on policies, not party. However, Cramer is popular in North Dakota as well, and he is both a Republican and conservative. North Dakota’s voting trends combined with their split-ballot history give no candidate a clear advantage. The last aspect of this race is the polling.

We have 4 polls since 2018, 2 using a generic Republican and 2 using Kevin Cramer. Also, 2 of the polls were conducted by a Republican pollster. Because of the difference in the polling, I’ll look at each poll individually. First of all, we have a poll from a Republican group putting a generic Republican 14 points ahead of a generic Democrat. While this seems extreme, this is to be expected, as Heitkamp is not a “generic” Democrat but rather quite conservative, relative to the party. Second, the same Republican group conducted a poll using Heitkamp and Cramer. This poll found Cramer leading Heitkamp by only 5 points. Given that this is a Republican polling group, the result points to a close race. Also notable, Heitkamp did 9 points better than the generic Democrat if you compare both polls. This is important because it shows the amount of crossover GOP voters there could be in November. The third poll was conducted using Heitkamp and a generic Republican. In a Republican state, a generic Republican tends to do better than usual. The poll found the Republican leading Heitkamp by 2 points, a practical tossup. The fourth poll was conducted using Heitkamp and Cramer, and it found Heitkamp up by 3 points. This is about what we would expect, given the partisan lean of the first two polls and the use of a generic Republican in the third. While using a simple average of the polls would show Cramer leading, looking at each poll individually shows a tight race, with Heitkamp barely edging out her opponent. It’s also worth noting that the polls that found Heitkamp in the best position were conducted most recently, though all were conducted in February. So, looking at the candidates, the voting trends, and the polls, I can confidently say that no one can confidently predict the winner.

My prediction showed a pure tossup until the last factor: Heitkamp is an incumbent, and in the midterms, opposition incumbents rarely lose. I rate North Dakota as leaning blue, but it could easily go Republican.


If North Dakota is the closest race, then Missouri is the second closest race, at least at face value. Of course, I don’t rate based on face value, so let’s get into the state, starting with the candidates. Claire McCaskill, the Democrat, is extremely lucky to be in the Senate in the first place. Had her opponent not said what he said about abortion and the female body, he probably would’ve won. However, she did win, and she proved to be a moderate. She’s voted with Trump 46% of the time. She is also exceptionally well at campaigning and is unlikely to make any mistakes or leave anything undone. Her opponent, Josh Hawley, is being affected by the unpopularity of the current GOP Governor in Missouri. Many want the Governor to resign or be impeached because of his scandal, and the GOP is seen poorly by a large percent of the state. However, this means nothing if Hawley isn’t associated with that. To determine this, we can look at the polls.

Of the six polls taken since 2018, McCaskill is leading in 4. One poll was taken by a Republican group and two were taken by a Democratic group. These polls found results that favored their alignment. The 3 most recent polls all favor McCaskill. Polling seems to clearly favor McCaskill, but only by a small margin, and all polling has errors. Before I can make a call, I have to look at the state’s voting trends. Missouri used to be a predictor state, meaning it always went for the winner. In 2008, that changed, but Obama only lost the state by 4,000 votes. Since then, it’s trended Republican, but not as much as Montana or North Dakota. They’ve elected McCaskill twice, though once was because of a flawed GOP candidate. This tells me that the voters, while preferring Republicans, have no problem voting for a moderate Democrat. With all that said, I think that Missouri leans blue.


Texas being competitive may come as a surprise to many people. Eight years ago, Texas would’ve been a sure thing for Republicans. Since 2000, it has trended towards the Democrats, going for Trump by only (still significantly) 9%. That’s about as competitive as Ohio was. That being said, Texas is still redder than the nation as a whole. In a wave election, that might not matter. Let’s look at the candidates. Ted Cruz is a strong Republican incumbent, and while he may be unpopular, he still got more votes than all of the Democrats combined in the primaries. Texans have shown that they’re willing to vote for Ted Cruz even if they don’t like him. On the other hand, Beto O’Rourke is a strong Democratic candidate who is loved by people who know him. The only problem: not many people know him. He visited every county in Texas before the primary, but still only got 62% of the Democratic vote. If Beto gets name recognition, he could prove to be a serious challenger. That’s not to mention he’s out-raised Ted Cruz and has millions of dollars in donations.

We do have two 2018 polls of this race. One, taken in January by a Democratic firm, showed Cruz ahead by 8 points. The other, taken in April by a “gold-standard” polling firm, showed Cruz up by 3 points. This points to a race that leans Republican but is competitive nonetheless. I think Texas leans red.


Wisconsin surprisingly went for Trump in 2018. Before then, it had gone Democratic for every President since 1984, the Reagan landslide. It does have a Republican Governor and a Republican Senator, but both seem to be in trouble in the re-election campaigns. We have a special data point in Wisconsin: a statewide special election. Just a month ago, Wisconsin held a nonpartisan election for their state Supreme Court.  The liberal candidate won by over ten points, a sizable swing from Trump’s narrow victory. The Democrats’ advantages don’t end there; Republicans don’t have a strong candidate to face Baldwin, who is the current incumbent. The leading nominee for the Republicans, Kevin Nicholson, was behind Baldwin by 13 points in a March poll. It doesn’t take long before Wisconsin can be seen as likely Democratic, making it the first “likely” rating thus far.


Indiana surprisingly went for Obama in ’08, but it has since trended back to the Republicans. Trump won the state by 20%. That being said, Joe Donnelly won the open seat by 6% in 2012. Like most Democrats mentioned here, Joe Donnelly is a moderate who has no trouble breaking with the party. He has voted with Trump the majority of the time. He is also well known in Indiana and has a positive approval rating. On the Republican side, the three-way primary between Messer, Rokita, and Braun looks like a dead heat. Rokita pollsters put him ahead, Messer pollsters put him tied with Rokita, and unaffiliated pollsters put Braun ahead. About 50% of respondents are undecided, so we’ll have to wait until the May 8th primaries to know who the nominee is. Regardless, Donnelly has a solid lead in the polls, averaging about 19% ahead of a Republican. I rate Indiana as lean blue.


Sherrod Brown is a rare liberal Democrat in a Trump state. Unlike other red-state Democrats, Brown is an average Democrat and votes with Trump less than 30% of the time. If he were running in North Dakota, he’d likely lose, but he’s running in Ohio. Ohio isn’t necessarily a “red” state. It voted for Obama twice, and last elected Brown by 6%. Brown still has a positive approval rating and is well known across the state. His Republican opponent is still undecided. Jim Renacci leads the polls, but over 50% are undecided. We’ll have to wait until May 8th to know the candidate. Brown leads by an average of 7 points against Renacci, and he leads by double digits against other Republicans. I think Ohio leans Democratic.

West Virginia

West Virginia’s a bit tricky. They’re considered safe Republican in Presidential elections now, but they have no trouble electing conservative Democrats statewide. Their Governor was elected as a Democrat but later switched to a Republican. Joe Manchin is a conservative Democrat, and he proves that in the Senate. He has voted with Trump over 61% of the time. He is popular and well respected in West Virginia, and he has personally worked with Trump before. The question is, will voters ditch him for a Republican?

We don’t have 2018 polls using candidates, but Manchin leads in every poll taken in this race dating back to 2016. This makes the race a bit harder to analyze, but it’s pretty clear the Manchin has an advantage over the Republican. Speaking of the Republican, we don’t know who it’ll be, although we do have primary polls. Evan Jenkins and Patrick Morrisey aren’t tied in any particular poll, but they each lead in about half of the 2018 polls. Don Blankenship, a Republican who famously called Mitch McConnell “Cocaine Mitch”, consistently gets about 15% of support in the polls. If he were to win the nomination, West Virginia would be likely Democratic. Evan Jenkins used to be a Democrat and is currently a Representative in Congress. If he were to win the nomination, West Virginia would be lean Democrat. Finally, Patrick Morrisey is a classic conservative who is currently the state’s Attorney General. If he were to win the nomination, West Virginia would be lean Democratic.

Looking at those ratings, and realizing that either Morrisey or Jenkins are favorites to win over Blankenship, I rate West Virginia as leaning Democratic, at least until the Republican nominee is chosen on May 8th.

Mississippi Open Seat

Another competitive seat emerged earlier when Thad Cochran announced his retirement. While Mississippi may seem like a stretch, stranger things have happened. This race is only competitive because of its nature: it’s a jungle primary, much like the GA-06 special, and there are no party labels on the ballot. Chris McDaniels, who was once primarying Roger Wicker, is running for the seat, as are a handful of other Republicans. Mike Espy, a Democrat running, is somewhat moderate. There is at least one other Democrat running. It seems unlikely that two Republicans could get into the runoff, but it is possible. Also technically possible: two Democrats could get into the runoff. That seems unlikely, but its something to consider.

The most likely runoff matchup includes Espy and some Republican, we’re just not sure which one, and there’s no good polling. Cindy Hyde-Smith is a frontrunner Republican who is much less controversial than McDaniels. She has an average polling lead of about 8 points in a potential runoff against Espy. McDaniels, on the other hand, is down by 2 points in one poll and 19 in another. It’s clear that he’s the weaker of the two Republicans, but it’s not clear whether or not he’ll make it to the runoff. The last possible solution: someone gets over 50% outright. It’s highly unlikely that this will happen, but its slightly more likely that Espy would get over 50%, rather than a Republican.

Right now, I’m rating Mississippi as likely Republican, but that will probably change based on who gets into the runoff, if there is one.


Florida’s Senate race got a little more interesting when Governor Rick Scott announced his candidacy. However, interesting doesn’t necessarily mean close, and Scott may prove to be a weak candidate. Let’s look at his past elections as Governor. When he was elected in 2010, he won by just over 1%, even though 2010 was a Republican wave year. In 2014, another Republican year and with Scott being an incumbent, he won by even less. This isn’t good for someone who’s running against a moderate incumbent. Meanwhile, Bill Nelson last won re-election in 2012 by 13%, despite Obama only winning the state by 1%. Going back to 2000, Nelson won Florida by nearly 5% while Bush “won” by a few votes. This paints a clear picture: Scott underperforms even in Republican years, and Nelson overperforms.

The only thing we have left to check is polling, because at the end of the day voters don’t care about trends. We have over 10 polls since the start of 2018, most of them with Nelson leading. There are some outliers: one poll has Scott leading by 10, while another has Nelson leading by 10. The average results of these polls give Nelson a fair lead. Given the weakness of Rick Scott, Florida is borderline likely Democratic, but for now, I’ll keep it as simply lean Democratic.


There’s a reason I saved Tennessee for last. It may not be the closest race, but it is the hardest to call. Phil Bredesen, the Democratic candidate, was an extremely popular Governor and won every single county. That doesn’t mean he’s going to win the Senate seat, but it gives him a needed boost in deep red Tennessee. Tennessee went for Trump by large margins, and it’s been trending Republican since the Bill Clinton era. However, its voters have proven that they are willing to vote for moderate Democrats like Bredesen. Bredesen was loved as Governor and helped the state get past tough economic times without creating a tax burden. His opponent Marsha Blackburn, is a Tennessee Representative but is not known state-wide. This wouldn’t be a problem if, say, outgoing Senator Bob Corker campaigned for her. He’s not. After speaking against Trump months ago and being a moderate in the Senate, he has announced that he will not be campaigning against Bredesen. He did say he would vote for Blackburn, but when asked why, he could only say that Blackburn would vote for Mitch McConnell. Basically, he’s saying that he’s voting for Blackburn because he wants Republicans to keep the majority, not because he likes Blackburn more than Bredesen. Voters can see this, and they may be turned off a candidate whose sole purpose is to keep McConnell the Majority Leader. Bredesen seems to be the better candidate, but will voters agree?

There have been 8 polls since 2018, and only 2 have the Republican leading. Some polls have given Bredesen as much as a 10 point lead in the Volunteer State. That’s surprising, to say the least, but understandable if voters remember Bredesen from his time as Governor and don’t focus on partisanship.

With polls and candidate strength going for Bredesen, it seems hard to rate this race as anything but lean blue. There’s just one thing holding me back: Trump won by 26 points. Without an incumbency boost, that seems simply out of range. In my previous post, I wrote that Democrats have seen about a 10-20% swing in special elections. To flip Tennessee, they’d have to swing the state by 26% + 1 vote, which is a lot. It seems like it can’t be done, but polls have been proving otherwise. Keep in mind that, since 2018, 6 polls have given Bredesen a lead, and 2 have given him a 10 point lead. As unrealistic as it may seem, I think Tennessee narrowly, narrowly, leans Democratic. If polls tighten up, I’ll probably change this rating, but for now, Bredesen is favored.

Final Map

My final map has Democrats coming out with 52 seats to the Republicans’ 48.

This would be a major flip for the Democrats and would probably give them control over the entire Congress. What does this mean? First of all, controversial Trump legislature and nominees probably wouldn’t pass. Congress could also pass bills protecting people like Robert Mueller, assuming that hasn’t happened yet. That’s the simple effects, but what about the deeper issues that will arise in a Democratic Senate? Moderate Senators like Heidi Heitkamp, Claire McCaskill, and Joe Manchin will recognize that their moderation is what gave Democrats the Senate. This could pull the Democratic Caucus as a whole more towards the right. Let’s look at an example: Heidi Heitkamp has been narrowly re-elected, putting the Democrats at at-least a 51 seat majority. She realizes that her constituents didn’t vote for her because she was a Democrat; they voted for her because she is moderate. If the Democrats try to push liberal policies through Congress, people like Heidi Heitkamp might block that legislature, just as Senator Susan Collins blocked conservative legislature from passing in a 52-48 Republican Senate. If the Democrats win the Senate, we will probably see a reverse of roles: moderate Republicans unite with Republicans while moderate Democrats will split on certain issues.

Thanks for reading my predictions. I update these about once a month, along with my Gubernatorial predictions.

About Holden

Holden is the creator of holdencasey.com. He is the lead editor and consistently writes about politics and finance. He often writes unbiasedly, but occasionally provides a liberal viewpoint in his work.
View all posts by Holden →

3 thoughts on “2018 Updated Senate Predictions

Leave a Reply

Your email address will not be published. Required fields are marked *