Trump, Biden clash in final debate on COVID-19 response, health care, race

In the wake of that canceled second showdown and a chaotic first debate before it, the Commission on Presidential Debates announced earlier this week it would mute candidates’ microphones at certain points Thursday to avoid interruptions and “maintain order.”

Trump and Biden will now have two minutes each of uninterrupted time to speak at the beginning of each 15-minute segment, of which there are six, in the 90-minute debate.

After the first four minutes of each segment, both of their microphones will go live for an “open-discussion portion,” the commission co-chair said. The moderator will not have control of the candidates' mics at any point. Those will instead be controlled by event production staff.

ABC News Chief Congressional Correspondent Mary Bruce said on ABC News Live Prime ahead of the debate, “Just because your microphone is down, doesn't mean that you necessarily will stop talking.”

Trump has attacked the integrity of the debate commission and its chosen moderators in recent weeks, deeming it all "crazy" and the new mic rule "very unfair” -- but sources have told ABC News Chief White House Correspondent Jonathan Karl that some advisers think muting the mics will actually help the president.

Biden, meanwhile, has called the muting of mics "a good idea" and said he’s expecting Trump to fire off personal attacks during their final showdown.

ABC News Chief Anchor George Stephanopoulos said the big question for Biden, who leads in nationwide polls, is whether he can close the deal with voters from Nashville. For Trump, it's how will he adjusts his performance after the "disastrous" first debate more than three weeks ago.

"Even the president's own aides called his blustering performance a self-inflicted wound," Stephanopoulos said.

Pick who wins the race: Forecast if Trump or Biden will win the 2020 presidential election with ABC News' interactive election map.

To win the presidency, candidates have to hit the magic number of 270 electoral votes. The Electoral College comprises a total of 538 members, with each state getting a total number of electoral votes equal to its congressional delegation and three additional electoral votes for District of Columbia.

American foreign policy for over half a century was defined by its bipartisan nature, symbolized in the old adage that politics stopped at the water's edge.

But in recent years, foreign policy has become as politically charged as virtually everything else in American life, and when voters mail in their ballots or go to the polls, they'll face a stark difference between the Republican and Democratic nominee and their views of the world and the United States' place in it.

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Trump vs. Biden on the issues: Foreign policy

An overview of the presidential candidates’ positions on various issues.

ABCNews.com

Ahead of Thursday's debate, the Trump campaign made an eleventh-hour demand that the questions focus on foreign policy, as opposed to the topics chosen by the moderator, though the campaigns agreed months ago to allowing the moderator to choose the debate topics.

Read about how Trump and Biden differ on major foreign policy issues including relations with China, Iran, North Korea and NATO allies, among others, here.

-ABC News’ Conor Finnegan

Aides to Trump and Biden separately reported their candidates tested negative for COVID-19 ahead of the final debate.

Earlier Thursday, White House press secretary Kayleigh McEnany told reporters that Trump had tested negative, and Trump’s chief of staff Mark Meadows said the president was tested during the flight from the Washington, D.C., area to Nashville.

They did not offer information on whether the people who accompanied Trump to Nashville -- including Ivanka Trump, Jared Kushner, Tiffany Trump, Bill Stepien, David Bossie and Robert O’Brien -- were tested.

] text=[MORE: Election 2020 live updates: 'I think the mute is very unfair': Trump on debate mics]/

Biden’s campaign said in an earlier statement the former vice president “underwent PCR testing for COVID-19 today and COVID-19 was not detected” -- his thirteenth negative test since the campaign began disclosing test results in the aftermath of the last debate and Trump’s positive diagnosis.

Biden told reporters on his way to Nashville that he'd hoped everyone got tested ahead of the debate.

At a NBC News town hall last week, Trump claimed he didn’t remember whether he’d been tested on the day of the first debate, which took place before his first positive COVID-19 test was reported.

-ABC News' Molly Nagle and Jordyn Phelps