Updated at 10:15 a.m. ET

Marc Short, the chief of staff to Vice President Pence, tested positive for the coronavirus on Saturday, making him the closest aide to Pence and the latest senior White House official to contract the virus.

The confirmation comes as Pence — who tested negative on Saturday — crisscrosses the U.S. for rallies in swing states in the remaining days of the campaign as he and President Trump fight to win reelection.

The White House says Pence will continue to campaign.

Trump's handling of the pandemic has been the central issue in the race. More than 224,000 people have died from the virus in the U.S., and more than 8 million people have been infected. Cases have been surging recently, and daily new case levels hit a record high on Friday. Millions of people have been thrown out of work because of shutdowns and other changes forced by the pandemic.

Short did not travel with Pence on Saturday to rallies in Lakeland and Tallahassee, Fla. Aides deemed to have had close contact with Short were pulled from the trip before departure, White House reporters who traveled with Pence were later told.

But Pence, who is considered to have had close contact with his most senior adviser, decided to "maintain his schedule in accordance with the CDC guidelines for essential personnel," spokesman Devin O'Malley said in a statement, noting that Pence had consulted with White House physicians.

The Centers for Disease Control and Prevention'sguidelines for essential workers who have had close contact with an infected person include wearing a mask for 14 days "at all times while in the workplace." Pence did not wear a mask at his outdoor rally. O'Malley could not be immediately reached for comment about whether Pence had worn a mask on Air Force Two.

Asked by CNN on Sunday whether Pence should continue to campaign, White House Chief of Staff Mark Meadows said: "Essential personnel, whether it's the vice president of the United States or anyone else, has to continue on."

O'Malley said Short "began quarantine" on Saturday and was "assisting in the contact tracing process."

Trump, who had the virus and was hospitalized this month, has insisted that the country has rounded the corner on the pandemic.

Asked about surging cases in Wisconsin — one of three states Trump visited for rallies on Saturday — he bristled and said most people who get the virus recover.

"You know why there are so many cases? Because we test," he said. "You're trying to scare people. Don't scare people."

Neither Trump nor his aides mentioned Short's diagnosis on Saturday as the president went to rallies in North Carolina, Ohio and Wisconsin. Upon landing after midnight, Trump told reporters that he had "just now" heard about Short's diagnosis. "I think he's quarantining," Trump said. "He's going to be fine."

Pence, who is the head of the White House's coronavirus task force, did not comment on Short's diagnosis on Saturday. In his second rally in Tallahassee, Pence didn't discuss the coronavirus until midway through his 50-minute speech, lauding Trump for his actions.

"Until that day that we have a vaccine available, we're going to keep working to slow the spread," Pence said. "We're all going to do our part to protect the vulnerable, to save lives."

Since last Sunday, Pence has appeared at 10 rallies in seven states: Maine, Pennsylvania, New Hampshire, Ohio, Michigan, Indiana and Florida.

His office said late Saturday that he would travel to a rally in Kinston, N.C., on Sunday, and the Trump campaign has also scheduled him for a rally in Hibbing, Minn., on Monday.

"Vice President Pence and Mrs. Pence both tested negative for COVID-19 today and remain in good health," O'Malley said.

Trump has sought to make his recovery from the virus an asset on the campaign trailafter the White House had its own "superspreader event" last month. More than a dozen people got the virus, including Trump; first lady Melania Trump; their teenage son, Barron; campaign manager Bill Stepien; press secretary Kayleigh McEnany; and adviser Hope Hicks. Trump has said their experience shows people can recover.

But polls show most Americans disapprove of how Trump has handled the pandemic. By a 71%-to-26% margin, likely voters view the coronavirus as a "real threat," though a significant portion of Republicans view it as being blown out of proportion, according to an NPR/PBS NewsHour/Marist poll.

The poll showed that only 36% of likely voters said they trust what Trump says about the virus a great deal or a good amount, and most said they would prefer Democratic presidential nominee Joe Biden to handle the issue.

The White House has refused to say how many staff members have contracted the virus in total. Medical experts have said the incident shows how lax Trump and officials have been in taking steps to stop the spread of the virus, including wearing masks and staying at least 6 feet away from other people — and how they've relied too much on testing.

WFSU's Ryan Dailey contributed to this story.

Copyright 2020 NPR. To see more, visit https://www.npr.org.