As the coronavirus pandemic continues to spread in the United States, members of Congress and their staffs are taking precautions to ensure they do not contract the disease or spread it to others — including social distancing, testing and self-quarantine.

Most recently, Sen. Lindsey Graham, R-S.C., tested negative for coronavirus on Sunday after self-quarantining following a trip to President Trump's Mar-a-Lago resort — where a member of the Brazilian president's delegation spent time before later testing positive for the novel coronavirus. The veteran senator tweeted that his test was negative.

"I was just informed by [Dr. Monahan], the head of the House Physicians Office, that my coronavirus test was NEGATIVE. I am very grateful and like everyone else will follow the best practices to stay negative," Graham tweeted. "I look forward to getting back to work with my Senate colleagues and President Trump to contain this virus and stabilize our economy. Thank you very much for all the prayers and well wishes!"

CORONAVIRUS: WHAT TO KNOW

TRUMP ATTEMPTS TO CALM COUNTRY AT WH CORONAVIRUS BRIEFING, SAYING 'NO NEED TO HOARD' SUPPLIES

Graham is one of several members of Congress to self-quarantine after potential exposure to the coronavirus -- a list that includes Rep. Don Beyer, D-Va., Rep. Matt Gaetz, R-Fla., Rep. Doug Collins, R-Ga. and others. No members have tested positive yet, but at least three congressional staff members have.

Two of those positive tests came Sunday night. The other was a member of Washington Sen. Maria Cantwell's staff last week.

Delaware Sen. Tom Carper's office said in a press release Sunday that one member of his state staff -- meaning the person did not spend time in Washington, D.C. -- tested positive for the coronavirus and was self-quarantining.

"On the advice of Delaware public health experts at the Delaware Department of Health and Social Services (DHSS), other members of Senator Carper’s staff who came in contact with the individual while the individual was exhibiting symptoms will be self-isolating at home for the next 14 days and monitoring their symptoms closely," the press release said. "If any of those staff members start showing symptoms of COVID-19, they will be tested as well."

HOUSE'S CORONAVIRUS BILL MAY BE IN TROUBLE IN THE SENATE

The release from Carper's office said all of his staff would begin teleworking on Monday.

Arizona GOP Rep. David Schweikert announced Sunday that a member of his Capitol Hill staff tested positive.

"They are resting comfortably at home and following guidance from local health officials," Schweikart said in a statement Sunday. "Given that I have interacted with the employee who tested positive, I will be working from home until otherwise told by doctors."

Schweikart is also closing both his Capitol Hill office and his office in Scottsdale, Ariz.

This all comes as House Speaker Nancy Pelosi, D-Calif., told all House members in a "Dear Colleague" letter to watch their health as they go to their home states this week for a district work period.

"In bipartisan consultation with the Attending Physician and the Sergeant at Arms, and out of an abundance of caution, I am writing to encourage you to take steps to promote social distancing within your Washington, D.C. office as we engage in the District Work Period. This may entail more than half of your Washington staff teleworking from home.," Pelosi said.

CLICK HERE TO GET THE FOX NEWS APP

She provided members with a link to coronavirus and telework FAQs as well as the CDC's steps to prevent the spread of the coronavirus before promising to keep Congress up-and-running. Fox News previously reported that one congressional source said one of the difficulties in negotiating the coronavirus bill passed last week was the fact "we could never get everyone in the same room," because legislators, staffers and members of the White House were practicing social distancing. Pelosi and Treasury Secretary Steven Munchen spoke on the phone more than 20 times on Friday.

"As this public health emergency develops, the House will continue to take strong, strategic and science-based action to keep the American people safe and ensure the continuity of Congressional operations (COOP)," the speaker said in her letter.

"I wish you and your family a healthy and productive District Work Period. Thank you for your continued leadership and patriotism during this difficult time."

Fox News' Nick Givas and Chad Pergram contributed to this report.