Donald Trump scowled and fumed and fussed and interrupted. On Monday night, he was forced to defend business practices that involved not paying workers and contractors, a tax plan that offers most of its benefits to the wealthy, the fact that he did not pay any federal taxes in some years (which he called “smart”) and the debt incurred by his businesses.

Hillary Clinton wanted to remind Americans of the Trump they had grown accustomed to disliking, the man who demeaned women, minorities and immigrants. Trump helped her out, even debating the moderator, Lester Holt, about “stop and frisk” police tactics. He grunted “ugh” when Clinton called out his sweeping comments on the allegedly parlous state of African American communities.

Trump again tried to put the birther issue behind him and failed. The man who built his base on the right end of the Republican Party by insinuating that President Obama was born abroad tried to slough off a question about what had once been his signature cause, but Clinton bore in and linked his treatment of the nation’s first African American president to what she called “his long record of racist behavior.”

[What worked for Trump in the primaries failed him against Clinton]

The surprise of the debate was that Clinton put before them a new Trump to dislike. Trump has campaigned as a populist paladin of the working class. But the Trump that Clinton described was a plutocrat who walked away from debts and obligations to his own employees. She pushed the debate into an extended discussion of how Trump had become wealthy and turned what he sees as one of his central assets, his business acumen, into what could become a big liability as the campaign goes forward.

Here are the key moments from the first 2016 presidential debate between Hillary Clinton and Donald Trump on Sept. 26. NBC Nightly News anchor Lester Holt moderated the debate at Hofstra University in New York. (Sarah Parnass/The Washington Post)

If one use of a debate for a candidate is to change the trajectory of the campaign discussion, Clinton may well have succeeded in opening a new front against Trump.

The debate was a slugfest that only occasionally veered into a discussion of issues. Clinton opened with a detailed list of her proposals, from investments in infrastructure, advanced manufacturing and clean energy to her plans for profit-sharing, paid family leave and debt-free college.

Trump’s presentation was light on specific proposals, except for his tax cuts. He opened with his signature attacks on free-trade agreements. He denounced both the North American Free Trade Agreement and the Trans-Pacific Partnership, and trade was one of the few issues on which he scored a clean hit on Clinton.

When Trump noted that she had called the TPP “the gold standard,” Clinton explained she had hoped the deal would be just that, but was unhappy with what emerged after it was negotiated.

[Trump bombs on the ultimate reality show]

“So is it President Obama’s fault?” Trump asked. It was not a question she could easily answer.

But this was the exception on an evening when Trump was on the defensive over and over again. He tried to defend his claim that he opposed the Iraq War despite evidence to the contrary — without much effect. His defense of his refusal to release his tax returns was ineffectual as he wandered into talk of being “underleveraged” and offered a confusing accounting tour of the worth of his buildings. Trump often looked rattled and impatient, sighing, frowning and offering answers that were a tangle of half-thoughts and odd asides.

Republican presidential nominee Donald Trump said Clinton didn't have "the stamina" to be president while responding to a question about his previous comments that Clinton lacks a presidential "look." (The Washington Post)

The final blow for Trump came when he decided to break with advice so many of his supporters had given him to lay off personal attacks on Clinton.

He could not stop himself, asserting that Clinton lacked “the stamina” to become president. Clinton calmly went through her record of negotiating cease-fires, peace deals, the release of political prisoners and her 11 hours of congressional testimony before the House Benghazi Committee. When Trump had done all those things, she said, “he can talk to me about stamina.” When Trump pressed on, Clinton got a chance to remind voters that he had called women “pigs, slobs and dogs.” It was devastating.

One major encounter does not necessarily decide an election. But this one showed a Trump who was ill-prepared, disorganized, petulant and — ironically, as he became ever more flummoxed toward the end of the debate — short on stamina. Clinton’s calm dissection of her foe reassured jittery supporters and no doubt shook many voters who were considering Trump. Clinton shifted the contest her way during her party’s convention. She did it again during Monday night’s debate.

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