MANCHESTER, N.H. — Sen. Kelly Ayotte, R-N.H., has tried for months to walk a high wire on the vexing subject of Donald Trump. This week, she fell off.

Her tumble, on what most of us would see as an easy question about whether Trump should be regarded as a “role model,” came during a debate Monday night with Gov. Maggie Hassan, her Democratic opponent. They are locked in an excruciatingly close Senate race.

Close, and crucial: The Democrats’ chances of taking control of the Senate are likely to hang on winning three states — New Hampshire, Pennsylvania and Indiana. This assumes they also maintain their current leads in Wisconsin and Illinois. The Democrats have longer shots at holding Nevada or taking North Carolina and Missouri.

Ever since she was first elected six years ago, Ayotte has been a generally well-liked figure, partly because of her mastery at appearing conservative to conservatives and moderate to moderates. That skill is especially important this year because 2016 is very different from 2010, when the Tea Party was on the march and the midterm turnout falloff created a more Republican electorate. This is a presidential year, which means higher and broader participation. It is also the year of Trump, about whom Ayotte has adopted a stance of strategic ambiguity.

This past spring, she was widely mocked in the national media — and sent many scurrying for a dictionary or a thesaurus — when she insisted that while she would “support” Trump,” she would not “endorse” him.

Her fine distinction was aimed at avoiding offense to Trump supporters, whose votes she certainly needs, while also reassuring his many detractors in this moderate state that she fully understands why they dislike a man given to misogyny, racism, Putin-love and dyspeptic 3:20 a.m. tweets.

“Senator Ayotte has done as good a job as one can about being separate from Trump,” said Fergus Cullen, a former Republican state chairman who is in his party’s Never Trump camp. “She has never appeared at any of his events. She has called him out six or seven times.”

But the problem with a position based on pure calculation is that it leaves you with no firm ground to stand on. When a surprise question comes your way, you lack sure instincts to guide you.

And that’s what happened when Ayotte was asked during Monday’s debate whether she thought Trump was a “role model” for children. Here, the support-but-not-endorse formulation wouldn’t do, so she initially tried to duck the question. Then came this exchange between Ayotte and local radio host Chris Ryan:

Ryan: “But would you, would you, and again, to the question, would you tell them to be like Donald Trump? Would you point to him as a role model?”

Ayotte: “I think that, certainly, there are many role models that we have. And I believe he can serve as president and so absolutely I would do that.”

The social-media response was instant and devastating. Ayotte’s campaign, quickly realizing she had blundered badly, executed a role-model flip-flop. It issued a statement declaring she “misspoke,” and on Tuesday, she told reporters that “neither Donald Trump nor Hillary Clinton have set a good example.”

But that “absolutely” is likely to be the Hassan campaign’s favorite word between now and Nov. 8. Ayotte’s abrupt reversal reinforces the Democrat’s overall campaign theme. Hassan underscored this when I interviewed her at a campaign event here Tuesday evening.

“What has been true about my opponent’s campaign is she seems to want to have it both ways,” Hassan said. “She votes one way in Washington and then speaks a different way in New Hampshire. And I think that that’s what you saw from her last night. She said ‘absolutely.’ Nothing can walk you back from ‘absolutely,’ no matter how much she tries.”

And here is where the Ayotte episode fits neatly with Indiana Gov. Mike Pence’s performance at the vice presidential debate on Tuesday. He won style points for being smooth, but staying smooth meant ignoring or denying most of what Trump has said and inventing a statesmanlike Trump who doesn’t actually exist.

So to Trump’s many ill effects on our politics, add another: the intellectual and moral corruption of the Republican Party. Too many Republicans outside the Never Trump ranks have to deceive themselves about who Trump is or deceive the public about how they really feel about him. Or they just try to slide by, day to day, hoping not to blurt out the word “absolutely” where this man is concerned.

E.J. Dionne Jr. is a columnist with The Washington Post. His email address is: ejdionne@washpost.com. Twitter: @EJDionne.