WASHINGTON - US Vice-President Mike Pence's chief of staff tested positive for the coronavirus on Saturday, according to the vice-president's press secretary.

"Today, Marc Short, Chief of Staff to the Vice-President, tested positive for COVID-19, began quarantine and assisting in the contact tracing process," Devin O'Malley, the press secretary, said in a statement. "Vice-President Pence and Mrs Pence both tested negative for COVID-19 today, and remain in good health."

"While Vice-President Pence is considered a close contact with Mr Short, in consultation with the White House Medical Unit, the Vice-President will maintain his schedule in accordance with the (Centers for Disease Control and Prevention) guidelines for essential personnel," O'Malley said.

Short has traveled extensively with Pence, who has maintained a busy campaign schedule.

In addition, Bloomberg News reported earlier Saturday that one of Pence's closest political advisers, Marty Obst, contracted the virus Wednesday. Though not a government employee, Obst has frequently been in contact with the vice-president, the outlet said, adding that he has not been in proximity with Pence since about a week ago.

On Saturday evening, Pence delivered a campaign speech in Tallahassee, Florida, during a journey in which Short did not accompany him. Short was with the vice-president on Thursday for a rally in Indiana.

Pence has kept an aggressive travel schedule in recent weeks, campaigning tirelessly for the Trump-Pence ticket as the Nov 3 Election Day approaches. He is expected to travel to North Carolina, Pennsylvania and Minnesota and other states in the coming days.

The vice-president's spokeswoman, Katie Miller, was diagnosed with COVID-19 in May, but has already recovered.