Harris-Trump debate live updates: Stage set for showdown in tight presidential race

Just hours away from the debate, a campaign source is setting expectations that Harris is not "underestimating" Trump's ability to debate, and that it would be a "mistake" to do so.

The Harris team expects Trump to be "good" at debating, stressing that Trump has done this more than anybody else, while it will be Harris's first presidential debate.

The Harris campaign is "happy to get under [Trump's] skin," and they hope that bringing former Trump officials into the spin room later this evening will accomplish this.

On a campaign call last night, a source said Harris is ready for any version of Trump that shows up -- whether it's the presidential Trump, the more mellow Trump during the Biden debate or a more aggressive version.

-ABC News' Selina Wang

The consequential Harris-Trump face-off will air live tonight at 9 p.m. ET on ABC and stream on ABC News Live, Disney+ and Hulu.

ABC News Live is available on Samsung TV+, The Roku Channel, Amazon Fire TV devices, YouTube, Tubi, the ABC app, and ABC.com.

ABC News Digital and 538 will live blog the latest from the debate stage with coverage, analysis and fact checks.

SiriusXM users can listen to the debate on Channel 370.

The prime-time pre-debate special, "Race for the White House," will air at 8 p.m. ET and stream on ABC's platforms.

Read more here.

Harris and Trump are facing off at a pivotal time, with just weeks until Election Day and days before some states begin the early voting process.

Hot-button political issues that are likely to be discussed by Harris and Trump include the economy and inflation, immigration, reproductive rights, and crime and gun violence.

Foreign policy and the state of democracy are also expected to come up.

Read more here.

President Joe Biden will be watching the debate from New York, where he's going to be for 9/11 memorial events, according to White House press secretary Karine Jean-Pierre.

"The president will definitely be watching," she said in Monday’s briefing.

Jean-Pierre wouldn't give details on any conversations about the debate between Harris and Biden or whether he's given her any takeaways from his own last face-off with Trump, but she said the president was "very proud" of Harris.

"What I can say is, that he'll be watching, he supports, obviously, the vice president, is very proud of her, and I just don't have anything else to add," she said.

- ABC News’ Cheyenne Haslett