Speaker Mike Johnson toiled on Tuesday to find the votes to squeeze the G.O.P. budget resolution through the House, facing potential defections from centrist Republicans fearing the plan would tee up deep Medicaid cuts and conservatives who want to slash federal spending even more deeply.
Mr. Johnson announced an evening vote on the budget outline, whose approval would clear the way to enact the major elements of President Trump’s domestic agenda, but it was not clear whether he would be able to muster the votes to adopt it.
At a news conference at the Capitol on Tuesday, Mr. Johnson said Republican leaders were “very close” to winning the votes they needed to do so, but signaled the vote could slip to later in the week.
“There may be a vote tonight,” he said. “There might not be.”
It was a familiar conundrum for the speaker, who is working to quell discontent from both flanks of his fractious conference, all while dealing with a razor-thin majority that will accommodate almost no defections. If all members were present and voting, Mr. Johnson could afford to lose no more than a single Republican, and a handful have already said they are against the measure.
Approval of the budget plan is a crucial first step for Republicans to smooth the way through Congress for a massive fiscal package using a process called reconciliation, which allows such bills to steer clear of a filibuster and pass the Senate on a simple majority vote.
The House blueprint calls for legislation that would add roughly $3 trillion to the deficit over a decade, while teeing up deep cuts in spending on health care and food programs for low-income people. That would help pay for $4.5 trillion in tax cuts. It also calls for raising the debt limit by $4 trillion.