WASHINGTON (AP) — House leaders’ plan for swift action on a $2.2 trillion package to ease the coronavirus pandemic ‘s devastating toll on the U.S. economy and health care system ran into complications Friday as a maverick conservative threatened to delay passage until most lawmakers return to Washington for a vote.

That left many angry lawmakers scrambling to return to the nation’s capital amid a pandemic in which Americans have been urged to self-quarantine or keep their distance from one another.

As the House gaveled into session Friday morning, there was no doubt that, one way or the other, the chamber would eventually give final congressional approval to the largest economic relief package in U.S. history.

But Rep. Thomas Massie, R-Ky., who’s opposed to the massive bill, set the House on edge by threatening to try to force a roll call vote. Party leaders had hoped to pass the measure by voice vote without lawmakers having to take the risk of traveling to Washington.

Massie took to Twitter to suggest he’d require a quorum of lawmakers — some 216 lawmakers — to be present and voting. Massie didn’t respond to a reporter’s requests for comment.

Numerous high-ranking Republicans have called Massie in an attempt to persuade him to let the voice vote proceed, according to a top House GOP aide. They included House Minority Leader Kevin McCarthy, R-Calif., and Rep. Mark Meadows, R-N.C., whom President Donald Trump has chosen as his new chief of staff.

If those efforts fail and a roll call is needed, Republicans believe they will have more than 100 of their members back at the Capitol, according to the aide, who spoke on condition of anonymity to describe private conversations.

Democratic leaders urged lawmakers who are “willing and able” to come to the Capitol to do so.

Massie’s move infuriated lawmakers, forcing many to trek to Washington for a vote they’re not even sure will occur. If a quorum can’t assemble Friday, more members would have to travel for a Saturday session.

“Heading to Washington to vote on pandemic legislation. Because of one Member of Congress refusing to allow emergency action entire Congress must be called back to vote in House,” Rep. Peter King, R-N.Y., wrote on Twitter. “Risk of infection and risk of legislation being delayed. Disgraceful. Irresponsible.”

South Dakota GOP Rep. Dusty Johnson posted a selfie photograph of himself and three other lawmakers from the upper Midwest traveling to Washington on an otherwise empty plane.