DEVELOPING: US House members are racing back to Washington, DC, amid the coronavirus outbreak, because leaders fear at least one Republican member will demand a recorded vote Friday.

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WASHINGTON — Democratic and Republican leaders are scrambling members of Congress back to Washington late Thursday night because they suddenly believe the $2 trillion economic relief package might not pass by the voice vote planned for Friday and could be delayed if at least 216 members don’t show up to vote on the floor.

Members are now racing to get back to D.C. by Friday morning — in the middle of the coronavirus pandemic — because leaders fear at least one member, likely Rep. Thomas Massie, R-Ky., will demand a recorded vote.

Rep. Fred Upton, R-Mich., wrote on Twitter Thursday evening: “The CARES Act is historic legislation, which is why I'm driving back to DC to help get this thing over the finish line.” The drive from his Kalamazoo-area district is nearly 10 hours back to Washington.

Other Democratic members were pointing a finger at Massie on Twitter as they hustled back to Washington.

"If you intend to delay passage of the #coronavirus relief bill tomorrow morning, please advise your 428 colleagues RIGHT NOW so we can book flights and expend ~$200,000 in taxpayer money to counter your principled but terribly misguided stunt. #thankyou," wrote Minnesota Rep. Dean Phillips.

"I am jumping on the red eye tonight... thanks Massie," Arizona Rep. Ruben Gallego tweeted.

“Members are advised that it is possible this measure will not pass by voice vote,” House Majority Leader Steny Hoyer’s office wrote in an advisory to members tonight.

Ultimately, passage isn’t in jeopardy — but it could be delayed for as long as it takes for 216 members to arrive in Washington. The House gavels in at 9 a.m. on Friday and is expected to have two hours of debate.

“You might have one grandstander,” President Trump said at his press briefing on Thursday. “It will pass. It will just take a little longer.” He has said he would sign the bill once it passes.

Massie’s office did not respond to a request for comment from NBC News.

Members have been scattered across the country as flights have been canceled and millions have sheltered in their homes amid the pandemic. Public health officials have said in the last 48 hours that anyone traveling from New York should quarantine for 14 days – which could affect many members of Congress. There are also two members who have tested positive for the virus and over a dozen more who are self-quarantining after possible exposure.

“Members are encouraged to follow the guidance of their local and state health officials, however if they are able and willing to be in Washington D.C. by 10:00 a.m. tomorrow, members are encouraged to do so with caution,” Hoyer’s notice to members said.

Massie has threatened to vote “no” on the package and told local and national media Thursday he was driving back to Washington for the vote. Earlier today, Massie tweeted the section of the Constitution that defines a quorum — a rule he could use to potentially derail the bill if enough of his colleagues aren’t present and voting.

The House needs a quorum — half its membership — to be present to pass a bill if any single member demands one. If no one asks for a quorum, it’s assumed a quorum exists. This is what would allow the House to act without a recorded vote, by voice or unanimous consent. There are currently 5 vacancies in the 435-member House, so 216 votes constitutes a majority.