Assuming this is true, it makes Paul Ryan’s decision to campaign with Trump this weekend in Wisconsin even stranger. This is the “run away!” stage for downballot Republicans, not the photo-op stage. Maybe Ryan’s simply resolved to be a good soldier for the nominee in the home stretch no matter what risks that might entail for his caucus. Think that’ll buy him any extra goodwill from Trump-loving, establishment-hating populists in the future?

Actually, maybe Ryan thinks we’re perilously close to the “Trump starts blaming Republicans for his looming defeat” stage and wants to show some team spirit in hopes of not being one of his targets. Either way, the most important presidential debate in modern American history is just three short days away.

Should Mr. Trump falter badly in his second debate with Hillary Clinton on Sunday in St. Louis, Republican congressional candidates may take it as a cue to flee openly from their nominee, said two senior Republicans involved at high levels of the campaign who spoke on the condition of anonymity because they were not authorized to discuss private party strategy.

Mr. Trump has already slipped perceptibly in public polls, trailing widely this week in Pennsylvania and by smaller margins in Florida and North Carolina — three states he cannot afford to lose. But private polling by both parties shows an even more precipitous drop, especially among independent voters, moderate Republicans and women, according to a dozen strategists from both parties who spoke on the condition of anonymity because the data was confidential.

Liesl Hickey, a Republican strategist involved in several House races in swing states, said she was dismayed by a sudden exodus of independent voters in more diverse parts of the country.

“They are really starting to pull away from Trump,” said Ms. Hickey, describing his soaring unpopularity with independents as entering “uncharted territory.”

It’s odd to me that private polling would be conspicuously more dour for Trump than public polls are, and in a nonpartisan way too. I can’t think of an obvious reason for that (here’s one theory) unless both parties are expecting a more Democratic-heavy electorate this fall than public pollsters are. Maybe they’re detecting a GOTV advantage for Clinton that’s larger than pollsters realize? This quote from Clinton campaign chief Robby Mook should be taken with a grain of salt, but it’s worth noting.

Incidentally, we may have already reached the “anti-Trump Republicans with nothing to lose start showing their cards” stage:

Speaking of the debate, Trump told the New York Post yesterday that he’s not planning to bring up Bill Clinton’s sexual misdeeds at Sunday’s debate despite sending some strong signals about that last week. (“I want to win this election on my policies for the future, not on Bill Clinton’s past.”) Presumably Kellyanne Conway and her polling team looked closely at that and concluded that it would backfire. It’s a hard argument to make, as noted before, because it would force Trump to focus on Hillary as an accomplice to Bill’s scandals when the average low-information voter probably views her as a prime victim of them. And if Trump got too mean with his attacks, it might convince even more undecided voters that he doesn’t have a “presidential temperament.” The best thing he can do to help himself on Sunday is stay calm, not let Clinton provoke him, frame her as the personification of a failed status quo, and sound like he knows what he’s talking about. But then, that was the game plan for debate one also and it didn’t work out.

Here’s Kelly Ayotte executing the “run away!” strategy in New Hampshire, notably after agreeing that Trump is a role model during the Senate debate there a few days ago. A new poll of NH out today has Trump down just two points, one of his best showings in the state ever; the same poll has Ayotte up more than six points over Maggie Hassan.