Supporters of President Trump cheer as he arrives at a campaign rally in Springfield, Mo., Sept. 21, 2018. (Mike Segar/Reuters)

The odds suggest that Republicans are poised for a rough night Tuesday. We know, we know. Polls, right? Who can trust polls after they got 2016 wrong, what with predicting a victory of 3.2 points for Hillary Clinton when she won the popular vote by, uh, only 2.1 points.

That aside, though, an 85 percent chance of Democrats gaining a majority in the House (as FiveThirtyEight currently has it) is not a 100 percent chance. If we held the election 20 times, in three of those elections, the Republicans would hold their majority. Next Tuesday might be one of those three.

One of the factors that will determine whether it is? Turnout. We know, we know. It all comes down to turnout. But, you know, it’s true. An unexpected surge in turnout from Democrats or Republicans and the models those polls are built on start moving possibilities around in short order.

So we embrace data like the numbers just released from Gallup, indicating the extent to which voters hope to send a message to the White House with their vote. This is the sort of thing that gets people off the couch on cold November Tuesdays: wanting to see their political opponents suffer a humiliating defeat.

Gallup’s been asking if votes are meant to send a message since 1998. In the six midterm elections since (including 2018), no president has inspired more voters to want to send a message of opposition than President Trump.


(Philip Bump/The Washington Post)

However!

We’ve seen polling from Pew Research Center and others showing that, while opposition to Trump is a powerful motivation for votes, interest in showing support has also motivated a lot of people. In Gallup’s data, fewer people want to send a message of support than one of opposition, but more people want to send a message overall than in past years, and the percentage saying they want to send a message of support is lower only than what George W. Bush enjoyed in 2002.


(Philip Bump/The Washington Post)

Bush, at that point, was still enjoying a boost following the terrorist attacks of Sept. 11, 2001.

Those numbers get more dramatic when we isolate Republicans and Democrats. Most Republicans (and Republican-leaning independents) say they want to send a message of support. Most Democrats say they play to cast a vote to send a message of opposition.

The percentages of each group that plans to send such a message, though, is higher than in past years. Combined, the interest from partisans in sending a message is much higher.


(Philip Bump/The Washington Post)

Why does this matter? Look at the past three cycles. In each case, the opposition very much wanted to send a message to the president. In each case, it did: The president’s party lost House seats in each election and lost the majority in two. But they didn’t enjoy the same level of enthusiasm from members of the party itself.

That’s our point. If Republicans really want to show support for Trump, they’ll go to the polls, perhaps more than pollsters expect.

But then there’s another bit of data in that Gallup report: 44 percent of Democrats say they’re more likely to vote solely to send that message of opposition. Only about 3 in 10 Republicans say they’re more likely to vote just to send a message.

If Democrats really want to show opposition to Trump, they’ll go to the polls, perhaps more than pollsters expect. FiveThirtyEight says the most likely outcome of the election is that the Democrats pick up 38 seats, but it’s about as likely that they gain 60 seats as the Republicans keeping the House.

We know, we know. Math.