Democrats are going to do even better than the polls suggest because Republican discouragement

I might guess Democrats are going to do even better than the polls suggest because Republican discouragement, mainly of about half of Republicans, with Trump, will cause them to turn out less, even though they respond to polls.

Yes. I think that's a quite plausible source of additional Democratic overperformance, and it is somewhat different from the usual argument about polling error.

The key distinction is between what people tell a pollster they intend to do and whether they actually bother to vote. If a Republican voter says, quite sincerely, "I'd vote Republican," but is increasingly disgusted with Trump, that person's answer gets counted in the generic-ballot poll even if, on Election Day, he thinks, Oh, hell, I don't care enough to go vote.

And there are some indications that your premise is not merely hypothetical. Recent reporting describes Republican enthusiasm as weaker than Democratic enthusiasm, while Trump's approval has fallen to about 33% overall and even his approval among Republicans has fallen to 72% in one recent poll.

More interestingly, the current Democratic advantage is already fairly substantial: Pew had Democrats ahead 43–37 on the generic congressional ballot in July, while Emerson's August poll had 51–43.

So I would model your idea this way:

Polling error needn't mean that people are lying to pollsters. It can mean that pollsters correctly measure preferences among respondents but imperfectly predict which respondents will actually vote.

And midterms are particularly vulnerable to that problem because turnout is much lower and more variable than in presidential elections.

There is an additional wrinkle that makes your hypothesis especially interesting: Republican discouragement and Democratic enthusiasm can reinforce one another. A demoralized Republican stays home, while a Democrat who is highly motivated to punish Trump turns out. That's a much larger electoral effect than simply moving one Republican from "Republican" to "undecided."

There is already some circumstantial evidence in that direction. The Axios analysis of the House race says Democrats have been outperforming their 2024 baseline by roughly 10 points in special elections, while currently leading the generic ballot by around six points.

I wouldn't assume that means Democrats are going to beat the polls by, say, another five points. The danger is that pollsters know about turnout effects and attempt to model them, so some of this should already be incorporated into likely-voter screens.

But your underlying point is good: if the Republican half of the electorate that has become unhappy with Trump is disproportionately less motivated to vote, the usual polling question can systematically overstate Republican electoral strength.

In fact, I'd regard "Republicans who still identify Republican but don't care enough to vote" as a potentially more consequential group than Republicans who have actually switched their stated preference to Democrats.

I remember holding my nose and voting for Nixon because I thought McGovern way too far to the left and unacceptably naive. That didn't mean I became a Republican.

Exactly. That's an important distinction—and a good historical example of it.

You could be anti-McGovern without being pro-Republican. Your Nixon vote represented a judgment about that particular election, not a change in political identity.

The same thing can happen in the other direction today:

• A Republican can remain a Republican.

• Still intend, in principle, to vote Republican.

• Still answer a poll that way.

• Yet be sufficiently disgusted or discouraged by Trump that he simply doesn't show up.

That's actually a more subtle phenomenon than party switching, and potentially harder for polling models to capture.

Your Nixon example also illustrates why I wouldn't automatically interpret a large number of people saying "I'm a Republican" as meaning "I am equally motivated to vote Republican in this election." Political identity is remarkably sticky; electoral enthusiasm isn't.

And there's a delicious irony here: you can have a substantial population of people who are Republicans on the questionnaire but Democrats in the actual vote—or nonvoters altogether. The latter two outcomes are electorally identical from the Democratic candidate's perspective.