Conservative Republicans in the House were in open revolt Thursday over their party’s major legislation to deliver President Donald Trump’s domestic agenda, threatening to derail the tax and budget measure over concerns that it would add too much to the deficit.

In the latest indication of the dissent in the GOP’s ranks, two Republicans, Reps. Chip Roy of Texas and Ralph Norman of South Carolina, told reporters they planned to vote against approving the legislation in the Budget Committee in a session planned for Friday.

Roy’s and Norman’s opposition alone would be enough to block the measure from reaching the floor, upending the party’s drive to push the legislation through the House before a Memorial Day recess. A number of other conservative, anti-spending Republicans sit on the panel and suggested they could follow suit.

“Right now, the House proposal fails to meet the moment,” Roy said. “It does not meaningfully change spending. Plus, many of the decent provisions and cuts don’t begin until 2029 and beyond. That is swamp accounting to dodge real savings.”

As the day began Thursday, Roy was alone in declaring his intention to tank the bill in committee — a declaration that came roughly half an hour after the Texas Republican entered a meeting in Speaker Mike Johnson’s office meant to assuage holdout lawmakers.

But by the afternoon, a growing number of Republicans on the panel were venting their frustrations with the measure, and it appeared that House GOP leaders lacked the support, for now, to push the legislation carrying Trump’s domestic agenda over its next hurdle.

“It’s clear we don’t know the true cost of this bill or whether it adheres to the Budget blueprint,” Rep. Josh Brecheen of Oklahoma wrote on social media. “We have a duty to know the true cost of this legislation before advancing it. If we are to operate in truth, we must have true numbers — even if that means taking some more time to obtain that truth.”

Another, Rep. Glenn Grothman of Wisconsin, declined to say how he planned to vote in committee but said the legislation “doesn’t seem that sincere” in its efforts to cut spending.

The bill would extend Trump’s 2017 tax cut and temporarily enact his campaign pledges not to tax tips or overtime pay. Cuts to Medicaid, food stamps and subsidies for clean energy would partly offset the roughly $3.8 trillion cost of those tax measures, as well as increased spending on the military and immigration enforcement.

Republicans like Roy are demanding changes to the bill, arguing that their leaders did not go far enough to cut federal spending. Some had earlier insisted that the final product add nothing to the deficit. The Committee for a Responsible Federal Budget, a nonpartisan group that calls for lower deficits, estimated that the bill would add roughly $3.3 trillion to the deficit over the next decade.

They are also unhappy that a number of the provisions in the legislation to cut spending — chief among them a measure imposing work requirements on childless Medicaid recipients without disabilities — would not kick in until 2029.

“On Medicaid work requirements: Start ‘em now,” Rep. Scott Perry of Pennsylvania wrote on social media. “The American People are sick of half measures. Some of my congressional colleagues want to do anything but LEGISLATE...”

Republican leaders had toiled to structure the legislation to protect their most politically vulnerable members from accusations that the party was moving to gut popular health care programs like Medicaid. They stopped short of a structural overhaul that would have made deep cuts to the program.

House Republican leaders were discussing rewriting the work requirements so they would take effect sooner in a bid to appease conservatives. But it is a treacherous balancing act for Johnson, who must try to satisfy his most conservative members agitating for significant spending cuts, and his swing-seat members who say voting for legislation taking an ax to widely used federal programs would send them to an early political retirement.