How to Watch the First Harris-Trump Debate

Vice President Kamala Harris and former President Donald J. Trump will meet for the first time in a televised debate on ABC in September, a critical test in a fluid campaign that should draw tens of millions of viewers and that once had appeared to be in doubt.

Mr. Trump had committed to the debate in May but wavered after President Biden, following a disastrous debate performance in late June, withdrew from the race in July.

The debate is scheduled for 9 p.m. Eastern time on Sept. 10, less than a week before early voting begins in Pennsylvania, a crucial battleground state. It will run for 90 minutes.

The National Constitution Center in Philadelphia will host the debate.

ABC will broadcast the debate, which it is producing in conjunction with its Philadelphia affiliate, WPVI-TV. ABC News Live, Disney+ and Hulu will stream the debate.

David Muir, the anchor of “World News Tonight,” and Linsey Davis, anchor of “ABC News Live Prime,” will be the moderators.

ABC has not yet announced the rules or whether there will be an in-person audience. During the CNN debate in June, there was no audience. The network, trying to prevent the candidates from interrupting each other, muted Mr. Trump’s and Mr. Biden’s microphones when it was not their turn to speak.

That is also not clear. Mr. Trump has said that he had agreed to two other debates, with NBC News and Fox News, while a spokesman for the Harris-Walz campaign said that Ms. Harris would debate Mr. Trump one more time in October assuming that he shows up for the ABC News debate.