Donald Trump has just had an extraordinarily bad week, and Hillary Clinton an extraordinarily good one; betting markets now put Mrs. Clinton’s odds of winning almost as high as they were just after the Democratic convention. But both Mrs. Clinton’s virtues and Mr. Trump’s vices have been obvious all along. How, then, did the race manage to get so close on the eve of the debate?

A lot of the answer, I’ve argued, lies in the behavior of the news media, which spent the month before the first debate jeering at Mrs. Clinton, portraying minor missteps as major sins and inventing fake scandals out of thin air. But let us not let everyone else off the hook. Mr. Trump couldn’t have gotten as far as he has without the support, active or de facto, of many people who understand perfectly well what he is and what his election would mean, but have chosen not to take a stand.

Let’s start with the Republican political establishment, which is supporting Mr. Trump just as if he were a normal presidential nominee.

I’ve had a lot of critical things to say about Mitch McConnell, the Senate majority leader, and Paul Ryan, the speaker of the House. One thing of which I would never accuse them, however, is stupidity. They know what kind of man they’re dealing with — but they are spending this election pretending that we’re having a serious discussion about policy, that a vote for Mr. Trump is simply a vote for lower marginal tax rates. And they should not be allowed to flush the fact of their Trump support down the memory hole when the election is behind us.