Harris used debate to define herself—and Trump

These were the competing visions of Kamala Harris that the Democratic nominee and her Republican rival, Donald Trump, offered in their much-hyped first debate. The principal task for both candidates going into their first-ever meeting was to define the race’s newer entrant, who remains an unknown quantity to many Americans after less than two months as her party’s suddenly-installed nominee.

But to a remarkable degree, it was Trump on the defensive as she jabbed at him relentlessly.

The result: Harris got ample opportunity to define both herself and her opponent—whom she often baited into validating her depiction of him as chaotic and self-centered. Trump continually indulged in grievances and fact-free rants. He repeatedly brought up President Biden, who dropped out of the race following his disastrous June 27 debate performance and Democratic concerns that he wasn’t up to the task of defeating Trump.

“Clearly, I am not Joe Biden. I am clearly not Donald Trump. And what I do offer is a new generation of leadership for our country, one who believes in what is possible, one who brings a sense of optimism," Harris said.

“She doesn’t have a plan. She copied Biden’s plan," Trump said. “It’s like four sentences, like ‘Run, Spot, Run.’"

In a race that polls show to be neck and neck, with less than two months to go before Election Day and some states already sending out ballots, the debate came with high stakes. The American electorate already knows Trump abundantly well after a polarizing near decade on the political stage. So it was Harris who political strategists viewed as having more to prove to a nation still unsure what her potential presidency would look like—or whether she is ready to step to the top job at all.

Harris’s attempts to get under her opponent’s skin—such as mentioning the crowd sizes at his rallies—sent Trump down discursive rabbit holes rather than consistently laying out a vision for the country in a second Trump term.

“She’s busing them in and paying them to be there," he said when she brought up his rally crowds. “People don’t leave my rallies. We have the biggest rallies, the most incredible rallies in the history of politics."

Unlike Harris, Trump made little attempt to pivot to the center of the electorate. And he couldn’t resist airing unfounded claims. He repeated a debunked rumor from the right-wing fever swamps about immigrants eating people’s pets in Ohio; he falsely insisted, again, that he won the 2020 election; and claimed the large crowds Harris had drawn to her campaign events weren’t real. Asked what he would propose to replace the Affordable Care Act, he said, “I have concepts of a plan."

To be sure, many voters will still have questions about Harris, what she stands for and why. Polling ahead of the debate showed many don’t know what to make of her, and Trump’s failure to press her may leave many of their questions unanswered. But in a sign of how good Harris’s camp believed the night went for them, her campaign immediately demanded another debate. And then she was endorsed by Taylor Swift, putting a final exclamation point on an evening most Democrats viewed as a triumph.

Trump’s campaign said Swift’s endorsement was further proof that Democrats are the party of the wealthy and the elite. On the Harris campaign’s calls for a second debate, Trump said: “She wants to do another one because she got beaten tonight." He added: “We’ll think about it."

The former president’s case against Harris was most pointed when it came to immigration. He repeatedly attacked Harris for recent years’ surge in illegal border crossings, and demanded to know why she didn’t prevail upon Biden to do more to secure the border. He also pointed to lower inflation during his presidency to argue that his tariff-based economic policies would make the country more prosperous, and attacked the administration’s clean-energy policies for driving up prices.

But he got bogged down defending his negotiations with the Taliban rather than take her to task for the Afghanistan withdrawal that remains the most unpopular moment of the Biden presidency. He fixated on the false claim that infanticide is legal in some states rather than answering yes or no on whether he would veto a national abortion ban. And when he tried to press Harris on late-term abortions, she retorted, “Why don’t you answer the question?" without answering the question herself.

Trump notably didn’t take the bait when asked about his past comments questioning Harris’s racial identity: “Whatever she wants to be is OK with me," he said, though he then went on to repeat his prior claim that she had only identified as Black when it suited her. In response, Harris recited a litany of Trump’s racial provocations. “I think the American people want better than that," she said.

During the debate, which Republicans criticized for uneven fact-checking of the nominees, Harris skated past questions about her prior opposition to fracking and support for socialized medicine. She pivoted frequently to policy and substance, repeating her proposals to give tax breaks to small businesses and increase the supply of housing. “Not everybody got handed $400 million on a silver platter and then filed bankruptcy six times," she jabbed.

At the debate’s last moment, as Trump gave his closing statement, he pointed out that Harris has had ample opportunity to implement the plans she says she has.

“She just started by saying she’s going to do this, she’s going to do that, she’s going to do all these wonderful things—why hasn’t she done it?" he asked. But Harris wouldn’t have to answer that question.

The debate was already over.

Write to Molly Ball at molly.ball@wsj.com