| Senate Democrats* | Senate Republicans |
| 11.4% probability of a majority | 88.6% probability of a majority |
| Mean of 48 seats | Mean of 52 seats |
Control of the Senate is up for grabs this fall. My previous analysis showed Democrats with a average of 49 seats and Republicans with 51 seats, putting the Democrats in range to flip the Senate. That was over a half year ago, so it is time to update the analysis using a plethora of new polls released since then.
After 100,000 simulated elections, Democrats have a Senate majority 1,914 times, (and there were 9,521 ties), and Republicans control the Senate 88,565 times. If the election was now, Democrats would have an 11.4% probability of controlling the Senate and Republicans an 88.6% probability of controlling the Senate. Of course, if Republicans end up in the White House, the ties would go to them.
Here is the distribution of Senate seats from the simulations:*
The most likely outcome is a 52 to 48 split with Republicans in charge. Here are some state-by-state comments.
Florida: Without question, the return of Marco Rubio to the Senate race has changed the likely outcome. Democrat Patrick Murphy has a fight on his hands. Polls occasionally favor Murphy, but the most likely outcome is a victory for Rubio (assuming they both come out on top in the August 30 primary).
FL polls
Illinois:
Republican Mark Kirk leads Democrat Tammy Duckworth in the only recent poll. Up ’till now, Kirk has been considered one of the most endangered Republican incumbents. Duckworth crushed Kirk a year ago, and then there was a long poll-less period. Clearly more Illinois polls are needed.
IL polls
Nevada: Harry Reid’s (D) seat is up for grabs with Catherine Cortez Masto (D) besting Joe Heck (R) based on two recent polls. Cortez Mastro only has a 67% probability of taking the seat based on these polls. Most older polls show Heck with the advantage. This one is a toss-up.
NV polls
New Hampshire: Sen. Kelly Ayotte (R) is facing a mighty challenge from Governor Maggie Hassan (D). The six current polls give the Democrat a slim 54% probability of taking the seat. This is, essentially, a tie, and the polling history shows this to be an extremely close race with a small advantage to Ayotte.
NH polls
Ohio: Sen. Rob Portman (R) has pulled ahead of former Gov. Ted Strickland (D), after Strickland led for most of the past year. Portman would win an election now with a 91.9% probablity.
OH polls
Wisconsin: Sen. Ron Johnson (R) is the most endangered sitting Senator in the country. He is likely to lose to former Sen. Russ Feingold (D), if the polling to date is any indication.
WI polls
This graphs shows the probability of at least each number of seats controlled by the Democrats:*
- 100000 simulations: Democrats control the Senate 11.4%, Republicans control the Senate 88.6%.
- Average ( SE) seats for Democrats: 48.2 ( 1.1)
- Average (SE) seats for Republicans: 51.8 ( 1.1)
- Median (95% CI) seats for Democrats: 48 (46, 50)
- Median (95% CI) seats for Republicans: 52 (50, 54)
Expected outcomes from the simulations:
- Democratic seats w/no election: 35
- Independent seats w/no election: one
- Republican seats w/no election: 30
- Contested Democratic seats likely to remain Democratic: ten
- Contested Republican seats likely to remain Republican: 22
- Contested Democratic seats likely to switch: none
- Contested Republican seats likely to switch: two
This table shows the number of Senate seats controlled for different criteria for the probability of winning a state:* Safe>0.9999, Strong>90%, Leans>60%, Weak>50%
| Threshold | Safe | + Strong | + Leans | + Weak |
|---|---|---|---|---|
| Safe Democrat | 45 | |||
| Strong Democrat | 1 | 46 | ||
| Leans Democrat | 1 | 1 | 47 | |
| Weak Democrat | 1 | 1 | 1 | 48 |
| Weak Republican | 0 | 0 | 0 | 52 |
| Leans Republican | 3 | 3 | 52 | |
| Strong Republican | 9 | 49 | ||
| Safe Republican | 40 |
This table summarizes the results by state. Click on the poll number to see the individual polls included for a state.
| # | Sample | Percent | Percent | Democrat | Republican | ||
|---|---|---|---|---|---|---|---|
| State | @ | polls | size | Democrat | Republican | % wins | % wins |
| AL | 0 | 0 | (0) | (100) | |||
| AK | 0 | 0 | (0) | (100) | |||
| AZ | 3 | 1511 | 48.7 | 51.3 | 23.7 | 76.3 | |
| AR | 1 | 601 | 36.3 | 63.7 | 0.0 | 100.0 | |
| CA | 1 | 602 | 62.0 | 38.0 | 100.0 | 0.0 | |
| CO | 4 | 2010 | 57.3 | 42.7 | 100.0 | 0.0 | |
| CT | 0 | 0 | (100) | (0) | |||
| FL | 7 | 5637 | 47.7 | 52.3 | 0.6 | 99.4 | |
| GA | 1 | 593 | 42.7 | 57.3 | 0.6 | 99.4 | |
| HI | 0 | 0 | (100) | (0) | |||
| ID | 0 | 0 | (0) | (100) | |||
| IL | 1 | 658 | 49.1 | 50.9 | 36.8 | 63.2 | |
| IN | 1& | 348 | 37.9 | 62.1 | 0.0 | 100.0 | |
| IA | 6 | 3836 | 45.9 | 54.1 | 0.0 | 100.0 | |
| KS | 1 | 458 | 38.9 | 61.1 | 0.0 | 100.0 | |
| KY | 0 | 0 | (0) | (100) | |||
| LA | 0 | 0 | (0) | (100) | |||
| MD | 1& | 686 | 67.9 | 32.1 | 100.0 | 0.0 | |
| MO | 1 | 757 | 48.1 | 51.9 | 23.0 | 77.0 | |
| NV | 2 | 1775 | 50.7 | 49.3 | 67.0 | 33.0 | |
| NH | 6 | 2775 | 50.2 | 49.8 | 54.0 | 46.0 | |
| NY | 3 | 2396 | 71.8 | 28.2 | 100.0 | 0.0 | |
| NC | 2 | 1536 | 47.0 | 53.0 | 4.8 | 95.2 | |
| ND | 0 | 0 | (0) | (100) | |||
| OH | 7 | 4883 | 48.6 | 51.4 | 8.1 | 91.9 | |
| OK | 0 | 0 | (0) | (100) | |||
| OR | 0 | 0 | (100) | (0) | |||
| PA | 5 | 4112 | 47.5 | 52.5 | 1.3 | 98.7 | |
| SC | 0 | 0 | (0) | (100) | |||
| SD | 0 | 0 | (0) | (100) | |||
| UT | 1 | 1113 | 43.9 | 56.1 | 0.2 | 99.8 | |
| VT | 0 | 0 | (100) | (0) | |||
| WA | 1& | 335 | 65.7 | 34.3 | 100.0 | 0.0 | |
| WI | 3 | 1968 | 54.7 | 45.3 | 99.8 | 0.2 |
@ Current party in office
& An older poll was used (i.e. no recent polls exist).
*Analyses assume that the two independent candidates will caucus with the Democrats.
Details of the methods are given in the FAQ.
I continue to be impressed by the standout States that will not vote for Donald Trump but will continue to elect and re-elect a lick spittle Republican foot soldier to serve his racist/nationalist agenda in the Senate. Democrats must do a better job of tying Republican candidates and incumbents to the racist/nationalist agenda they support.
If Republicans hold the Senate, and Trump somehow wins the White House, Democrats’ best hope is a civil war within the GOP, which is not outside the realm of possibility.
The Rubio-Murphy race would be a wash anyway, Murphy’s record shows he would vote with the Republicans most of the time. Or as I would say to Republicans: Pouring money down drain to elect people who won’t vote the way you want — sad!
Republicans maintaining their Senate majority relies significantly on re-electing “moderate” Republicans who frequently defy the whip on key legislation. And part of what makes the Republican majority vulnerable has been their willingness to eat their own for lack of orthodoxy. Democrats might take a lesson from that.
There’s plenty wrong with Murphy in Florida that should disqualify him from the Senate aside from his willingness to break bread with Republicans. But I’m not willing to extend that judgment to other conservative Democrats in the Senate. Demands for ideological purity, stupid pledges, and oppressive leadership are what put the Republican party in the fix they are in. I don’t want to see Democrats make the same mistakes. Now that Republicans are voting in large numbers for fascist authoritarian lunatics, the stakes are simply too high. I’ll gladly take incrementalism over burning the Constitution.
Debbie Wassermann Schultz surely showed everyone she did her best to put the fix in to keep Bernie Sanders out. Bernie’s supporters are fairly pissed about the whole thing. Washerman Shultz is a contemptible character. Hell, she’d make a fine Republican!
California doesn’t deserve a state-by-state comment?
Republicans maintaining their Senate majority relies significantly on re-electing “moderate” Republicans who frequently defy the whip on key legislation. And part of what makes the Republican majority vulnerable has been their willingness to eat their own for lack of orthodoxy. Democrats might take a lesson from that.
Manchin, Heitkamp defy their Dem elders on when needed, as well.
Each are pretty well ensconced in their positions. Which Dem senators aren’t sufficiently progressive so as to threaten their re-election? Most of those have already left voluntarily (Bayh, although he wants back in) or been bounced in wave elections.
Speaking of Bayh @ 7, I’d say Indiana is worth of some additional comment, even if there isn’t poll data of late. It ain’t gonna go 62:38 anymore.
Using the assumption the incumbent will win, and showing open seats as a toss up will probably get you to similar numbers with a lot less effort. Oddly recently incumbents losing their primary has become slightly more likely. Of course here in Washington State we could get 2 democrats running for the seat. If that happens a lot of pressure will be brought to bear on the current system. The Senate will likely remain Republican…looks like Hilliary Clinton thinks so based on her VP pick.
@8 True. Bush was so bad, Obama won Indiana in ’08.
Mark Adams @ 9,
“Using the assumption the incumbent will win, and showing open seats as a toss up will probably get you to similar numbers with a lot less effort. “
No…actually it wouldn’t.
And feel free to NOT read any of the many analyses yet to come this election season.
@ 10
Hey Roger Dumbfuck Rabbit:
Can you think of a reason I brought up Indiana in a US Senate thread that has absolutely nothing to do with George W. Bush?
Something, perhaps, having to do with the candidates in the one poll taken in that state and included in this analysis?
@12,
I expect there are a considerable number of ticket splitting voters in Indiana who may be willing to vote for Bayh, even if they hate Clinton. This will be more of a test for the Cheeto Jesus team than for Clinton. I know if I’m Evan Bayh I don’t want the Clinton bear hug. But I want the money, the voter data, and the outreach.
Will Pence be effective? Perhaps. But much will depend on Trump. So far Trump has demonstrated very little understanding of these down ballot nuances. More public polling now that Bayh is in will clarify. But I certainly have to belive that internal polling was done prior. If the GOP spent their VP selection to hold on to a single Senate seat, that says a lot about their state of decline.
@ 13
Not really prepared to go any further than:
Baron Hill was an awful candidate.
Evan Bayh is far from awful.
That was really the point I was attempting to convey.
@14,
But isn’t it fun to speculate about the chess game?
I mean, I think Bayh was far from assured of winning prior to the Pence pick. And it would seem that if the DNC were plotting which states to flip they’d have looked elsewhere first. But that presumes that the DNC is a player in that sense. By now we should know better. More logical to speculate that some select handful of non-government, non-party power brokers well known to Bayh though his lobbying work persuaded him to jump in once it was clear that Cheeto Jesus would be the nominee. With money and polling laid out before him, and an unspeakably negative Republican Presidential nominee to play off of, the water seemed just right. Then the RNC floats a turd in the shallow end and Bayh is gazing wistfully at his lobby firm chaise. Might still be a toss up. But I’d give the edge to Young. Still, it begs a bunch of questions: Does Pence really help Trump in swing states? Can Pence really make a difference for Young? Is it worth vacating a Governor’s mansion? Is it worth vacating an unsafe House seat? And how does that little girl with the pet dragons figure into it?
My guess is Trump’s second thoughts arrived just about the time somebody (named Newt) showed him how his pick was being employed for other interests. Plenty of people are watching Indiana very closely this year. I’m hoping to see more evidence that the religious right has overplayed its hand.
@12 My my, you’re thin-skinned, Bob. Are polls getting to you already? It isn’t even August yet.
@11 To be effective and meaningful a poll has to be predictive beyond chance. Open seats are the interesting ones as both parties have a shot even in if the state is deep blue or red.
If incumbants will win 90 percent of the races (or higher) then only three maybe four races will flip. Since more Republicans are running those seats that flip are more likely to come from the Republicans than Democrats.
The graphs, polls and all are not telling me anything a rational person could state back in 2015 about the upcoming Senate races. I also think your model must be biased as it’s showing 1 weak democratic candidate and yet your model states no Democratic seats will switch. For that reason alone I can conclude your model is biased.
Now the American people could make this an election where they throw the rascals out of office, and a bunch of Republicans will get booted and a smaller number of Deomocrats, but the Democrats would probably get in charge of the Senate, but Hilliary is playing things safe and the Republican’s who could get the boot are distancing themselves from Trump and the party. Assuming correctly their folks back in their state will return them to office.
@11 Don’t worry I’ll read them. They are good for a chuckle or two, and become more meaningful as the election looms closer. Still if Patty Murray doesn’t get on the ballot out of the Primary or should actually get beat (by a Democrat?) Republican I’d have to point out an over reliance on polls, though even my logic would not see that one coming. That is what makes politics and political prediction so much fun. Almost as much fun as March madness.
I think your models are biased perhaps this is because the site supports Democratics. It’s perfectly ok for you all to have that bias, but ideally the polls and model should be neutral and truthful. If it’s not I will point out there is bias, Now if it’s a Democratic your bias will be covered up, if it’s a Republican you will get some egg on your face. And if the American public has gone bat shit crazy you will be looking for a new mirror to ask who is the fairest politician in the land.
Uh oh.
Why are your results so different than five thirty eights?