White House staff have been ordered to wear a mask or facial covering to enter the West Wing, as Donald Trump confronts cases of the coronavirus at the heart of his administration.

Two known cases of Covid-19 among employees in one of the most-protected complexes in America have sent three of the nation's top medical experts into quarantine and vice president Mike Pence into self-isolation.

The scare comes as the White House this week emphasise to the American people the steps being taken to assure their safety - in hopes that will coax them to resume normal activities.

Staff will be allowed to remove face coverings if they sit at least six feet apart from colleagues. Mr Trump himself is still not expected to wear a mask.

Mr Pence on Monday led the White House's weekly call with governors from an isolated room after his press secretary tested positive on Friday.

Dr Deborah Birx and other staff participated as usual from the Situation Room, Mr Pence said, explaining the "slightly different circumstance".

"We are taking the appropriate countermeasures to protect the president's health," he added. The White House is moving to daily testing of some staff members to detect the disease.

The stepped-up protective measures comes as Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, Robert Redfield, director of the Centers for Disease Control and Prevention, and Stephen Hahn, commissioner of the Food and Drug Administration, were all quarantining after exposure to the White House employee.

The three experts are scheduled to give evidence to a Senate panel on Tuesday on "Safely Getting Back to Work and Back to School". They and committee chairman Lamar Alexander will participate remotely. Mr Alexander is quarantining after a staff member of his own tested positive for Covid-19.

The images of senior administration officials taking such precautions came as states sought to loosen economic restrictions put in place to mitigate the virus's spread.

Mr Trump complained on Monday that Democratic governors were too slow in lifting restrictions in their states.

He is scheduled to travel to the state on Thursday, according to advisories from the Federal Aviation Administration.

Alongside Mr Trump's encouragement to reopen, the administration moved on Monday to address significant death rates in nursing homes and other senior care facilities.

On the call with governors, Mr Pence and Dr Birx recommended that every occupant and employee be tested for Covid-19 in the next two weeks, with vigilant monitoring going forward, especially of staff.

More than 80,000 people have died in the United States from the coronavirus pandemic, according to the latest figures from Johns Hopkins University, by far the highest death toll of any country.

The US has struggled to quell the spread of the virus, with more than 1.3 million cases. New York has been the hardest hit state, with more than 26,600 declared deaths.