But that basic rule of thumb got a little more tricky for Ms. Harris. With Mr. Trump’s Covid-19 diagnosis and him just being back at the White House after three nights in a hospital, harsh attacks against an ailing president might be politically unwise. The Biden campaign pulled down its negative advertising attacking Mr. Trump as soon as he disclosed his diagnosis. Joseph R. Biden Jr. has stepped carefully in talking about the president.
Ms. Harris, a former prosecutor and a member of the Senate Judiciary Committee, has established her credentials as a tough interrogator with her questioning of officials like William P. Barr, the attorney general. She knows how to make a case. But can she attack Mr. Trump’s handling of the virus — which has come to define his presidency — without veering toward an overly personal attack on a president battling a potentially lethal disease?
It means threading a needle. Ms. Harris was an inconsistent debater during the Democratic primary — she had some good moments, and some not-so-good moments before she dropped out. She has never stepped onto a this prominent a stage.
How does Harris handle going off script?
Ms. Harris, most often remembered for her “that little girl was me” debate moment with Mr. Biden during the primary, is talented at delivering the slashing-when-prepared debate lines. That is, after all, the same skill set that she developed as a prosecutor and that elevated her during Senate committee hearings to star status among Democrats as she has bore in on Republican witnesses.
To that end, Ms. Harris arrived in Salt Lake City last Friday — the same day Mr. Trump was checked into the hospital — to begin her on-the-ground debate preparations. Karen Dunn, who readied Senator Tim Kaine to debate against Mr. Pence four years ago, is leading those efforts, which have also included Rohini Kosoglu, Symone Sanders and Liz Allen. Pete Buttigieg, who has played the role of Mr. Pence in Ms. Harris’s preparations, was spotted in town as well.
But debates are not set pieces and Ms. Harris will have to defend not just her own record but also Mr. Biden’s — and no candidate can be prepared for every eventuality, no matter how many index cards she studies, especially in 2020.
“This time it will be about requiring some level of knowledge — if not mastery — of Joe’s record, the Vice President Mike Pence’s record, Trump’s record and then of course defending my own record,” Ms. Harris said on Hillary Clinton’s podcast last week. “So that’s different.’’
Notably, Mr. Biden has undertaken some public rehearsals for his debates, including two televised town halls. Ms. Harris has been mostly cloistered since joining the ticket. The debate will be, by far, the most freewheeling exchanges of her time as vice-presidential candidate.
Credit…Joe Buglewicz for The New York Times
How race and gender play
Mrs. Clinton, the only woman to serve as a major-party presidential nominee, warned Ms. Harris, in so many words, about the corrosive role that sexism will play onstage.
“You should also be prepared for the slights, the efforts to diminish you, you personally, you as a woman, who is about to be our next vice president,” Mrs. Clinton said on her podcast. “So I do think there will be a lot of maneuvering on the other side to try to put you in a box.”
