NASHVILLE, Tenn. (AP) — While millions of people are watching on television, only around 200 are inside the massive college arena in Nashville where President Donald Trump and his Democratic challenger, Joe Biden, are facing off in their second and final debate of the 2020 election.

One of those 200 is controlling a mute button.

A representative of the Commission on Presidential Debates — not the moderator — is supposed to ensure each candidate has a two full minutes of uninterrupted time to deliver opening answers on six major topics, according to debate commission chair Frank Fahrenkopf. A member of each of the the Trump and Biden campaigns was expected to monitor the person who controls the mute button backstage, Fahrenkopf told The Associated Press, noting that the button would not be used beyond the first four minutes of each topic.

The mute button is among a handful of changes implemented by the nonpartisan debate commission to help ensure a more orderly debate following the raucous and widely-criticized opening debate 23 days ago. Trump was diagnosed with COVID-19 two days after the event and he and the White House have refused to say whether he abided by commission rules and tested negative for the virus before that debate.

Trump was given a test aboard Air Force One en route to Nashville Thursday and tested negative, White House chief of staff Mark Meadows said.

Organizers initially planned to separate the candidates with plexiglass barriers, but removed them hours before the debate began. A Trump campaign official said the decision was made after Meadows called Anthony Fauci, the nation's highly respected top infectious diseases expert, during a walkthrough of the venue site, and he said all it would do was provide a false sense of security.

Additionally, any audience member who refuses to wear a mask will be removed, organizers said. Last month, several members of the Trump family removed their masks once seated in the debate hall, but were allowed to stay.

Before the debate began, Fahrenkopf repeated the instruction to the small audience.

“If you won’t leave, you’ll be escorted," he said.

Fahrenkopf said in an earlier interview that the safety measures would help reduce the risk of infection. He also acknowledged that the Trump campaign opposed the use of plexiglass, just as it did ahead of the vice presidential debate earlier this month.

“The Trump campaign's attitude was that the president was not contagious anymore, but we’re going to go with our medical advisers," he said.

Indeed, the president of the university called it “the safest place in America tonight."

The primetime affair is playing out inside a 90,000-square-foot (8,360-square-meter) arena at Belmont University, a picturesque institution of more than 8,200 students just a mile from Nashville's music row. The university also hosted a town hall-style debate between Democrat Barack Obama and Republican John McCain in 2008.

There is a far smaller audience this time around.

The debate commission said that only around 200 people would be allowed inside, a mix of invited guests of the campaigns and the debate commission, students, the commission's production team, security, and health and safety personnel. Audience members were seated in accordance with social distancing recommendations; several empty seats separated each person or small group.

All audience members and support staff were required to undergo coronavirus testing onsite within three days of the event. They wore colored wrist bands as evidence of their negative tests.

There were several layers of security protecting the attendees, and dozens of protesters gathered just off campus beyond the security perimeter. One of them held a large white sign: “220,000 DEAD... Trump FAILED US.”

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Colvin reported from Washington.

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This story has been corrected to show that the vice presidential debate was earlier this month, not one week ago.