Credit Doug Mills/The New York Times
Mr. Trump’s attacks on a former beauty pageant winner were “unhinged,” Mrs. Clinton said, “even for Trump.” She accused him of valuing women only for their looks. She defended Rosie O’Donnell (“an accomplished actor”) and Kim Kardashian against his “pathetic” insults.
After 20 minutes, Mrs. Clinton concluded with a brief, discordant programming note for the afternoon: “We’ll be in Florida talking about national service,” she said. “You’ll want to watch.”
Limping out of a summer focused almost exclusively on discrediting Mr. Trump, the Clinton campaign has strained in recent weeks to migrate to a more positive message, convening high-minded speeches about Mrs. Clinton’s faith, career and public service aims — only to see Mr. Trump briefly catch her in the polls.
But in her surgical debate performance and the days that followed, Mrs. Clinton has regained her footing by reverting to form: disparaging Mr. Trump, setting traps for him and amplifying his howls when he finds himself ensnared in them.
“This is our reality,” Jennifer Palmieri, Mrs. Clinton’s communications director, told reporters on Friday, adding that the campaign was operating “on two tracks.”
“There’s a positive message that she’s delivering,” Ms. Palmieri said, “but she’s also going to call him out.”
Often, Mr. Trump has helped her cause, escalating a feud with a pageant winner, Alicia Machado, whom Mrs. Clinton mentioned during the debate to highlight his history of critical comments about the appearance of women.
Yet Mrs. Clinton’s team has been more than reactive, taking care to taunt and prod Mr. Trump with new urgency in recent days, even if it means overwhelming her own affirmative case.
Speaking to reporters on Thursday aboard her campaign plane, Mrs. Clinton boasted about “what we’re doing in our campaign, talking about a positive agenda, talking about how we are stronger together, laying out our plans.”
Then she turned to Mr. Trump.
“We already know about his tax returns that he refuses to release,” she said ominously, “but today we learned about his efforts to do business in Cuba, which appear to violate U.S. law.”
Mrs. Clinton had not been asked a question.
Last week, Mrs. Clinton scarcely alluded to Mr. Trump in a speech about people with disabilities, earning praise from some viewers by leaving a familiar attack — Mr. Trump’s mockery of a reporter’s physical disability — unsaid.
Hours later, though, the campaign hosted a conference call with supporters to hammer Mr. Trump on the subject, calling his behavior “unconscionable.”
Much had been made by Mrs. Clinton’s aides about a series of speeches, branded with a “Stronger Together” theme, aimed at shifting the conversation from political mudslinging to her more optimistic vision for the future.
Credit Doug Mills/The New York Times
When Mrs. Clinton returned to the campaign trail last month after recovering from pneumonia, she declared that, upon reflection, she was determined to make her bid about her goals as president, not simply a referendum against Mr. Trump.
“I want to close my campaign focused on opportunities for kids and fairness for families,” Mrs. Clinton told a crowd in Greensboro, N.C. “I want to give Americans something to vote for, not just against.”
But her addresses have been drowned out, not just by Mr. Trump’s antics but because of Mrs. Clinton’s own relentless assault on her Republican rival.
Ms. Palmieri said the chief goal of the first presidential debate was “distilling the best argument for her.”
In fact, what has resonated most is Mrs. Clinton’s journey through a trove of opposition research about Mr. Trump: his comments about Ms. Machado, his business practices and his failure to disclose his personal income taxes.
“She has to say it’s about issues and she has to talk about issues while campaigning because it’s one of the contrasts she’s making with Trump,” said Anna Greenberg, a Democratic strategist. “But he’s digging his own grave. They’d be committing malpractice if they weren’t helping him along with that.”
“They understand that this is the campaign they’re in,” Ms. Greenberg added, “and so it’s how it has to be fought.”
This reality has remained a source of alarm for some liberal Democrats who fear that Mrs. Clinton has waited too long to sell voters, especially former supporters of Senator Bernie Sanders, on a forceful case for her own candidacy.
Jonathan Tasini, a former union leader and Sanders supporter who challenged Mrs. Clinton in her Senate primary in 2006, said that Mr. Trump’s behavior made it “almost too hard to resist” engaging with him nonstop.
“I am mostly concerned about younger voters who have already made a decision never to vote for Trump,” he said, “but will simply stay home if she doesn’t offer a compelling vision of transformation that energizes them to get to the polls.”
The Machado episode, which has, remarkably, come to dominate a full week of a presidential campaign that is entering the stretch run, speaks to the delicate balance Mrs. Clinton has sought.
She began her Friday with the barrage of Twitter messages, responding to Mr. Trump’s own overnight fusillade, during which he insinuated that Ms. Machado had a sordid past.
“What kind of man stays up all night to smear a woman with lies and conspiracy theories?” Mrs. Clinton asked.
A short while later in Fort Pierce, Fla., before a backdrop that read “Do all the good” — a shortened version of a Methodist creed she often quotes — Mrs. Clinton praised the bipartisan tradition of national service, quoting Alexis de Tocqueville to extol the virtues of volunteerism.
“Some might say, ‘Well, hey, my gosh, you’ve only got 39 days to go. Why aren’t you just out there beating up on your opponent and doing everything to get the vote out?’” Mrs. Clinton said, punching at the air like a wayward boxer. “Well, I’ll do that.”
Later in the afternoon, at a speech in Coral Springs, Fla., Mrs. Clinton delivered on that promise.
“I mean, really,” she began, “who gets up at 3 o’clock in the morning to engage in a Twitter attack against a former Miss Universe?”