The Commission on Presidential Debates said Tuesday night that Vice President Pence had dropped his objections to a plexiglass barricade on his side of the stage for Wednesday’s debate after viewing the setup during a walk-through of the debate hall.

The disclosure, by commission co-chair Frank Fahrenkopf Jr., came after a long day of posturing between the Trump and Biden campaigns over whether the barriers were needed to protect the participants from the coronavirus. Advisers to Pence maintained that there was no need for a barrier on his side of the stage.

But at that point the stage was already being built with two clear dividers, one next to each of the tables where the candidates will sit. Fahrenkopf said he had multiple talks with representatives of the Pence campaign after they saw the layout of the stage.

“They said if Senator Harris feels safer to have two plexiglass dividers up, we have no objections,” Fahrenkopf said in an interview.

The detente, however, came just as another complication hit the debate preparations when Trump aide Stephen Miller tested positive for the coronavirus. He is married to one of Pence’s top staffers, Katie Miller, who had traveled to Salt Lake City to help the vice president, potentially jeopardizing her involvement in the event.

She had previously been infected with the disease, and it was not clear what effect her husband’s diagnosis would have on the Pence entourage. The University of Utah, the site of the debate, has a policy requiring a 14-day self-quarantine for anyone exposed to someone with covid-19.

Fahrenkopf said Tuesday night that no decision had been made about Miller’s situation. “At this point in time, we have no position,” he said. “We will find out in the morning.”

The resolution over the physical barriers at the debate culminated a day of verbal sniping between the Trump and Biden campaigns after an announcement Monday by the Commission on Presidential Debates that dividers had been agreed to as a safety measure.

Marc Short, the vice president’s chief of staff, said the vice president’s team did not view plexiglass dividers as medically necessary, given other safety measures at the debate, including a 12-foot distance between Pence and Sen. Kamala D. Harris (D-Calif.) and daily testing of both candidates.

“If she wants it, she’s more than welcome to surround herself with plexiglass if that makes her feel more comfortable,” Short said earlier in the day. “It’s not needed.”

Later, Short said the Pence team still believed there was no reason for plexiglass but confirmed that they had agreed to it nonetheless.

Utah is in the red zone for coronavirus cases, with 208 new cases per 100,000 people in the last week, according to a weekly report from the White House Coronavirus Task Force. That compared to a national average of 90 new cases per 100,000.

The dispute played into a larger clash of messages between the Trump and Biden campaigns. Trump argues that the coronavirus has largely been conquered and there is no need for burdensome restrictions; Biden’s campaign has focused sharply on a critique of the president’s handling of the pandemic. For both sides, plexiglass dividers could be seen as a symbol of the continued threat posed by the virus.

“ ‘It’s not needed’ is the latest iteration of ‘it is what it is,’ another example of the Trump administration’s abdication of leadership when it comes to the coronavirus pandemic,” Biden campaign spokesman Andrew Bates said in response to Short’s comment.

In the debate itself, Biden advisers said they expect Harris to press Pence, who leads the White House coronavirus task force, on the administration’s response to covid-19.

But they also say that the debate is likely to be more about Biden and Trump than their running mates, and that Harris’s primary focus will be casting Biden as a more capable and empathetic leader when it comes to the coronavirus and other issues, including the economy and racial justice.

Other safety measures were also the subject of extended negotiation. Both campaigns agreed last week to extend the distance between Pence and Harris from about seven feet to 12 feet.

The Biden camp has sought to stress that it is following the science, including the guidelines provided by the Cleveland Clinic, the medical adviser to the debates.

“The Cleveland Clinic is responsible for the safety of the debate. We will abide by their determination on safety measures,” said a Biden campaign official, who spoke on the condition of anonymity to discuss deliberations. “All questions about the adequacy of the safety measures should be addressed to the Cleveland Clinic.”

The Cleveland Clinic has so far declined to disclose its recommendations to the debate participants, beyond saying its guidelines “are based on scientific data, guidelines from the Centers for Disease Control and Prevention and medical advice.”

“Any questions regarding the recommendations and requirements, including their implementation and enforcement, should be directed to the CPD,” the clinic said in an unsigned statement Tuesday.

The Commission on Presidential Debates has promised to expel anyone from the debate hall in Utah who does not follow a mandate to wear a mask indoors. That mandate was disregarded by members of Trump's family at the first debate.

Both campaigns are aware that the outcome of the negotiations could create a precedent for the remaining presidential debates between Biden and Trump. Biden and Trump are scheduled to meet again on Oct. 15 and 22 for two more debates.

Trump, who was released from the hospital Monday, said Tuesday that he intended to take part in the next debate, tweeting, “I am looking forward to the debate on the evening of Thursday, October 15 in Miami. It will be great!”

Biden’s aides have said the former vice president will attend if Trump is medically cleared and the debate follows public health guidelines. But the former vice president added Tuesday, “I think if he still has covid, we shouldn’t have a debate.”

Pence attended a White House Rose Garden ceremony with several people who have since tested positive on Sept. 26, 11 days before Wednesday’s debate. He sat immediately in front of Sen. Mike Lee (R-Utah), three rows in front of White House press secretary Kayleigh McEnany and five seats away from Sen. Thom Tillis (R-N.C.).

All three have since tested positive for the virus, along with at least 11 others who had contact with the White House or the Trump campaign.

Pence’s team contended Tuesday morning that Pence had did not come close to anyone who contracted the virus.

“Under the guidelines of the Centers for Disease Control, the Vice President is not considered a close contact with any individuals who have tested positive for the coronavirus, including President Donald Trump,” Jesse Schonau, physician to the vice president, wrote in a letter Friday. “Vice President Pence does not need to quarantine.”

CDC Director Robert R. Redfield in a letter Tuesday echoed that finding, based on Schonau’s description of Pence’s interactions.

“The CDC concludes from a public health standpoint, it is safe for the Vice President to participate in the upcoming Vice-Presidential debate,” Redfield wrote.

Katie Miller, the Pence spokeswoman, said Pence was last in the Oval Office two days before Trump’s test, and was not within six feet of the president for more than 15 minutes.

The University of Utah has campus guidelines that follow federal health standards. Any faculty member who has “close contact” with someone who tests positive or has coronavirus symptoms is asked to self-quarantine for 14 days and self-monitor for symptoms.

“It would be the expectation that anyone (including visitors) on our campus would be following our fall semester guidelines,” said Chris Nelson, a spokesman for the University of Utah, in a statement via text message, ­before Stephen Miller’s diagnosis.

Negotiations over specifics of the Oct. 15 presidential debate have not yet begun, say people involved in the planning. The safety precautions are likely to hinge on the medical condition of the president.

“Assuming the president is negative, we are happy to have him debate on Oct. 15,” said Miami Mayor Francis X. Suarez (R), who had to isolate for 18 days earlier this year after contracting the coronavirus. He said he waited until two consecutive negative tests before interacting with people again.

“I can’t imagine a scenario under which the president or anyone would not be in quarantine if they are still positive,” Suarez said.

The CDC does not offer fixed guidance for when covid-19 patients can leave isolation.

“For most people with covid-19 illness, isolation and precautions can generally be discontinued 10 days after symptom onset and resolution of fever for at least 24 hours, without the use of fever-reducing medications, and with improvement of other symptoms,” the agency’s website says.

But those with more severe illness may need to wait longer, the agency says.Trump has ­exhibited symptoms including fever and fatigue and brief drops in oxygen levels, according to his medical staff, but the severity of his illness remains unclear.

Matt Viser, Chelsea Janes, Lena H. Sun and Annie Linskey contributed to this report.