Former President Donald J. Trump and Vice President Kamala Harris enter the homestretch of the campaign in a tight race, and with their only scheduled debate looming on Tuesday, Ms. Harris faces a sizable share of voters who still say they need to know more about her.

A national poll of likely voters by The New York Times and Siena College found Mr. Trump leading Ms. Harris, 48 percent to 47 percent, within the poll’s three-percentage-point margin of error and largely unchanged from a Times/Siena poll taken in late July just after President Biden dropped his re-election bid. Mr. Trump may have had a rough month following the president’s departure and amid the burst of excitement that Ms. Harris brought Democrats, but the poll suggests his support remains remarkably resilient.

[The result is surprising, Nate Cohn writes. But it’s also plausible the poll is the first to capture a shift back toward Donald Trump.]

The national results are in line with polls in the seven battleground states that will decide the presidential election, where Ms. Harris is tied with Mr. Trump or holds slim leads, according to New York Times polling averages. Taken together, they show a tight race that remains either candidate’s to win or lose.

Only a little over eight weeks remain in the shortest presidential election in modern American history. Both candidates have scant opportunity to shift the electorate, but for Mr. Trump, opinions are largely fixed. Ms. Harris is still unknown to many.