Washington CNN  — 

Trump administration officials spent the weekend scrambling after two staffers tested positive for coronavirus, bringing the pandemic closer to President Donald Trump even as he works to reopen parts of the country.

On Saturday and Sunday, aides attempted to conduct contact tracing for Katie Miller, Vice President Mike Pence’s press secretary who tested positive for coronavirus last week. But they had not identified who Miller contracted the virus from as of Sunday, raising concerns inside the White House about how to contain the outbreak.

On Monday, staffers were advised in a memo they would be required to wear a face covering when entering the West Wing, a person familiar said. The memo said face coverings would be available in the White House medical office and told staffers to follow social distancing guidelines.

Previously, masks were an uncommon sight at the White House, despite guidelines from the US Centers for Disease Control and Prevention recommending them in environments hwere social distancing is difficult.

Trump himself has said he cannot envision wearing a mask in public, and many of his aides take their direction from him. Nevertheless, the pair of staffers testing positive caused widespread concern among aides and led to new protocols meant to avoid further cases.

Some aides expressed concern at how Monday would proceed without greater clarity on how the virus had originated and spread. One official said it wasn’t certain which colleagues would stay home. Some officials who had extended contact with Miller announced they would self-quarantine, while others who had similar contact with her did not.

Meanwhile, aides were also trying to determine who came into contact with the military valet who tested positive last week. It appeared the valet’s contacts with other members of the West Wing staff were limited, but there remain some concerns among other valets and staff.

Trump’s top aides were repeatedly tested throughout the weekend and a trip to Camp David was called off in part because of concerns about coronavirus, two people familiar with the situation told CNN. One official said the weather also played an additional factor in scrapping the trip. A slew of officials, including the President, were at Camp David the weekend before with Miller.

In conversations this weekend, Trump has expressed concern that aides contracting coronavirus would undercut his message that the outbreak is waning and states should begin reopening, according to a person who spoke with him.

Trump voiced frustration that two White House staffers tested positive for coronavirus and has asked why his valets weren’t ordered to wear masks before this week, according to the person.

Trump believes an economic rebound will only come when governors decide to lift restrictions and is concerned at any signs the virus is resurgent.

At the same time, he’s told people he doesn’t want to be near anyone who hasn’t been tested and has bristled when coming into contact with some people at the White House.

Pence is not planning to enter self-quarantine and plans to be at the White House on Monday, his office said on Sunday.

CNN’s Kristen Holmes contributed to this report.