But she needs to do more, and she needs to do it quickly. Ms. Harris ought to challenge Mr. Trump to a series of debates or town halls on subjects of national importance, such as the economy, foreign policy, health care and immigration. Mr. Trump claims that he is ready and willing to participate in debates once Democrats have officially selected a nominee. Americans would benefit from comparing the two candidates directly.

Both candidates need to start taking questions from reporters, too. Candidates have abundant opportunities to speak directly to voters, through social media and tightly controlled public appearances, without the mediation of journalists. Most voters, however, will never be able to speak directly with candidates. President Biden has rarely granted the news media permission to ask questions on behalf of the American people, and on the rare occasions he did, his team sometimes sent scripted questions. It left him poorly prepared for the campaign trail and for confronting his opponent. Mr. Trump, too, rarely takes questions. Ms. Harris has the chance to do better.

Engaging with voters is especially important for Ms. Harris because she would be the first major-party presidential candidate in modern times who did not pass through the state primary process, in which voters have a chance to take the measure of candidates and to ask questions about the issues that matter most to their communities.