Here are the highlights from Donald Trump and Hillary Clinton sparring over the Republican nominee's history with questioning President Obama's place of birth. (The Washington Post)

Here are the highlights from Donald Trump and Hillary Clinton sparring over the Republican nominee's history with questioning President Obama's place of birth. (The Washington Post)

The moment when Donald Trump’s fortunes turned sharply south in the first presidential debate began like any other moment in his confident, loose-tongued campaign. Moderator Lester Holt asked why it took Trump “so long” to assess that President Obama was born in the United States. “I’ll tell you,” said Trump, “it’s very simple to say.”

What followed was anything but simple. “Sidney Blumenthal works for the campaign and a very close friend of Secretary Clinton,” Trump began. “And her campaign manager, Patti Doyle, went to — during her campaign against President Obama, fought very hard. And you can go look it up, and you can check it out. And if you look at CNN this past week, Patti Solis Doyle was on Wolf Blitzer saying that this happened.”

As Holt would point out, Trump had spent a few months in 2011 — and a few days every following year — speculating that the president was hiding something about his citizenship. But over several excruciating minutes, Trump struggled to explain himself. Within an hour, allies of his campaign were criticizing Holt for asking the question at all.

Trump’s stumble featured two habits that had worked on the campaign trail but melted in the direct light of the debate. The first was his attempt to frame old quotes or events in a more flattering way. The second was a reliance on sympathetic conservative news sources to accept his framing. What had worked in primary debates and countless phoned-in Fox News interviews came across onstage as gibberish.

“Blumenthal sent McClatchy, a highly respected reporter at McClatchy to Kenya to find out about it,” Trump said of the birth certificate. “They were pressing it very hard. She failed to get the birth certificate. When I got involved, I didn’t fail. I got him to give the birth certificate. So I’m satisfied with it, and I’ll tell you why I’m satisfied with it.”

Trump was referring to a claim by a former McClatchy journalist that Blumenthal, a close Clinton friend who did not work for her campaign, had pushed the rumor that Obama, then competing against Clinton for the 2008 Democratic presidential nomination, was born in Kenya. But Solis Doyle had not confirmed any 2008 “birther” rumor-mongering. As she quickly tweeted, she’d done the opposite — and had fired a Clinton volunteer who spread a rumor.

At no point during the debate did Trump actually explain what either Clinton ally did. What was clear is that he was unready to explain himself to a skeptical audience. In the weeks since he called a news conference to insist that Clinton “started the birther” movement, Trump had only defended himself with sympathetic media, including Fox News. When Holt began to ask what Trump would say to people who were offended, Trump was blunt: “I say nothing because I was able to get him to produce it.”

[Trump starts subdued, but his cool quickly melts.]

Clinton’s counterpunch was as direct as Trump had been rambling. Three times, she said that Trump had engaged in “racist” behavior — an anvil-drop of an accusation never before made in presidential debates. Clinton worked in a 1973 case brought against Trump’s company for racial discrimination, one of many damaging stories that had been lost in campaign coverage. Trump’s response was another ramble, indulging his bad habit of laboriously explaining his company’s legal battles. “We settled the suit with zero — with no admission of guilt,” he said. “It was very easy to do. But they sued many people.”

It was immediately clear to Trump’s campaign staff and surrogates that he had mangled the “birther” question. What had been cocksure pre-debate spin — Trump did not need to practice for these events — morphed into post-debate hand-wringing about Holt.

Trump communications director Jason Miller insisted that Trump had been clear, and viewers had learned that Trump was blameless for “birtherism.” When a reporter told Sarah Huckabee Sanders that the answer had been hard to parse, she joked that she “might be smarter” than the reporter — she had heard Trump just fine.

“What I didn’t think was fair was that we didn’t talk about the Clinton Foundation, we didn’t talk about Benghazi, we didn’t really talk about the email scandal,” Huckabee Sanders said.

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)

The spin emphasized just how many mistakes Trump had made with his approach — and why he’d made them. For five years, Trump had floated the idea that the president was ineligible for office (or hiding something about his past) in interviews where he bulldozed his questioners. More recently, he had stopped holding news conferences where reporters could test his defenses, focusing instead on prepared speeches and hand-holding interviews with media personalities including Sean Hannity.

One apparent result was the loss of Trump’s ability to pivot, from a question he was uncomfortable with to a subject he wanted to discuss. Before the “birther” exchange, Trump took a few opportunities to turn a question about his vulnerabilities into one about Clinton’s. After the exchange, he was so bogged down that he did not even mention the 2012 terrorist attack in Benghazi, a linchpin of his case against Clinton, when the Democratic nominee defended her record.

[Donald Trump was out of his depth. Here’s the answer that exemplifies it.]

In the post-debate spin room, Trump’s surrogates began defending his performance by casting it as relatable. Trump, they insisted, had been earthy and “human,” while Clinton had been “canned.”

Few reporters bought it. Sen. Jeff Sessions (R-Ala.), the first senator to endorse Trump and by far the most important in shaping his policy, was asked by one conservative outlet if it was “malpractice” for Trump to be baited so easily.

“Look, whenever I’ve done a debate, I can’t sleep at night thinking of things I could’ve, should’ve said,” argued Sessions. “So if you think you’re so good at it, you try. I mean, it’s no fun.”