Donald Trump doesn’t seem to have a good handle on what’s going on in the Senate races this year. After previously predicting that Sen. Jeff Flake of Arizona would lose in the fall (Flake isn’t up for re-election this year), Trump went after Sen. Kelly Ayotte of New Hampshire this week, saying, “I’m beating her in the polls by a lot.” But Ayotte is running ahead of Trump in New Hampshire, earning a higher share of support in her race than Trump is against Hillary Clinton in the Granite State.

In fact, Republicans in most Senate battlegrounds are running ahead of Trump in their states. That may last, increasing the chances that the GOP hangs on to their Senate majority. But it’s also possible that Trump begins to drag down his party’s down-ballot candidates.

Right now, Republicans hold 54 Senate seats to the Democrats’ 46. In order to take control of the Senate, Democrats need to pick up four seats if Clinton wins the presidency and five if she doesn’t. Of the 34 Senate seats up for grabs in 2016, here are the 10 that are closest to changing parties, according to the current polling averages: Arizona, Florida, Illinois, Missouri, Nevada, New Hampshire, North Carolina, Ohio, Pennsylvania and Wisconsin. All these seats, with the exception of Nevada’s, are currently held by Republicans, so Democrats need to win five of them to pick up a net gain of four and win six to pick up a net gain of five. (I’m not including the Indiana Senate election, which was shaken up by the late entrance of Democrat Evan Bayh. We have only one poll for the race, which comes from the Democratic Senatorial Campaign Committee.)

Trump is doing far worse in these states than the Republicans running for Senate in them, as the chart below shows:

POLLING MARGIN STATE GOP SENATE CANDIDATE TRUMP DIFFERENCE Arizona +5 +1 +4 Florida +5 -4 +9 Illinois -1 -18 +17 Missouri +7 +4 +3 Nevada +3 -3 +6 New Hampshire +2 -2 +4 North Carolina +4 -1 +5 Ohio +4 -4 +8 Pennsylvania +2 -6 +8 Wisconsin -8 -9 +1 Average +6.5 Trump’s running behind Republican Senate candidates in key states As of 4:05 p.m. Aug. 3 Source: HuffPost Pollster

In all but one of these 10 states, Trump is clearly running behind the Republican candidate for Senate. The only state where Trump isn’t doing at least 3 percentage points worse than his party’s Senate candidate is Wisconsin, where he is still running behind Sen. Ron Johnson at this time. On average, Trump is running nearly 7 percentage points behind the Republican candidates for Senate.

Now, no one expects that Trump should be out-polling Sen. Mark Kirk in Illinois, given the state’s deep blue lean on the presidential level. But the rest of these states tend to be winnable for Republicans in presidential elections.

Trump is currently trailing Clinton in eight of these 10 states, including crucial tipping-point states such as Florida and Ohio. The two states where he isn’t trailing Clinton, Arizona and Missouri, haven’t voted for a Democratic presidential candidate since 1996. Even in these states, though, the Republican candidates for Senate (Sen. Roy Blunt in Missouri and Sen. John McCain in Arizona) are doing better than Trump is there.

Unless Trump’s position improves, Republicans will be able to maintain control of the Senate only if enough voters split their tickets, voting Republican for the Senate but not in the presidential race. And the polls suggest that could happen: The Republican candidate for Senate is leading in a number of states where Trump is facing a deficit. At the moment, Sen. Marco Rubio is up in Florida, Joe Heck is ahead in Nevada (which would be a Republican pickup of Sen. Harry Reid’s seat), Sen. Richard Burr leads in North Carolina, Sen. Rob Portman is holding off Ted Strickland in Ohio, and Sen. Pat Toomey is hanging on in Pennsylvania.

But all those Republican candidates are leading by 5 percentage points or less. In the last presidential election cycle, 2012, a number of Republican Senate candidates faded down the stretch, and some, such as Tommy Thompson in Wisconsin, lost healthy-sized leads as the summer turned to fall. In an era in which fewer people are splitting their tickets, the advantages currently enjoyed by the Republican candidates for Senate aren’t secure. If Trump’s troubles continue or worsen, he could take down these Republican candidates with them.

One place where we might be seeing that already is New Hampshire. A new poll there taken after the Democratic convention by MassINC for WBUR shows Trump down 15 percentage points and Ayotte down 10 points. While that result may not reflect where the New Hampshire race eventually settles after the Democratic convention bounce fades, the poll points to potential trouble for Republicans in other battleground states. In looking at the crosstabs, MassINC pollster Steve Koczela told me that it was interesting “how closely tied the Ayotte and Trump vote are. I’d see that as evidence that Trump is hurting her.” In other words, voters’ views on Trump may be influencing their Senate vote. If that happens across the country and Trump continues to trail, it could lead to a Democratic majority in the Senate come 2017.





FiveThirtyEight: What’s happening to the Republican Party?