Rep. Chip Roy, R-Texas, blocked a $19.1 billion disaster relief bill that was expected to sail through Friday, a move that stalled the measure from becoming law.
The bill was expected to pass the House under a unanimous consent process, to which any member may object. It is likely to be revisited when lawmakers return June 3.
"I'm here today primarily because if I do not object Congress will have passed into law a bill that spends $19 billion of taxpayer money without members of Congress being present here in our nation's capital to vote on it," Roy said on the House floor.
"Secondly, it's a bill that includes nothing to address the clear national emergency and humanitarian crisis we face at our southern border," Roy said.
Democrats' next move was not immediately clear. Rep. Steny Hoyer, D-Md., the House majority leader, said the party will "take action as early as next week" during an informal session.
A companion measure passed in the Senate on Thursday. The bill included about $1 billion in funding for Puerto Rico relief, a point of contention, in addition to funds for other parts of the country hit by floods, hurricanes and fires.
President Donald Trump has declared the situation on the southern border a national emergency and had previously sought to include border-related funding in the bill. He later dropped the demand.
Roy's last-minute announcement immediately drew the fury of House Democrats.
"After President Trump and Senate Republicans delayed disaster relief for more than four months, it is deeply disappointing that House Republicans are now making disaster victims wait even longer to get the help they need," House Appropriations Committee Chairwoman Rep. Nita Lowey, D-N.Y., said in a statement.
House Speaker Nancy Pelosi, D-Calif., decried the move as "sabotage."
Roy previously served as the chief of staff to Sen. Ted Cruz, R-Texas. He was narrowly elected to his first term in Congress last year after pledging to secure the border "so that terrorists, criminals, and illegal immigrants are not allowed to come and go as they please," according to his campaign website.
Roy was elected with just over 50% of the vote in a district Trump carried by 10 points in 2016, suggesting he could face a difficult re-election battle. His district, Texas's 21st, is a "top tier Democratic pickup opportunity," according to Avery Jaffe, a spokesperson for the Democratic Congressional Campaign Committee.
"Every day Congressman Roy spends in Washington he turns more into a creature of the swamp," Jaffe said in a statement.
Roy, in a statement later Friday, wrote that "I stayed in D.C. to object because this kind of swampy practice is what Texans elected me to stand against.