House Republicans held a marathon markup session Thursday to push forward a budget blueprint that will tee up President Trump’s agenda of steep spending cuts and sweeping tax cuts.

The budget plan calls for a baseline of $1.5 trillion in spending cuts over a decade, a $4.5 trillion ceiling for tax cuts, a $4 trillion statutory increase to the nation’s debt ceiling and billions in new spending for defense, immigration and border security.

“This budget resolution provides the fiscal framework for what will be one of the most consequential pieces of legislation in modern history, and the principal legislative vehicle for delivering on President Trump’s America First agenda,” House Budget Committee Chair Jodey Arrington, Texas Republican, said as he opened the hearing.

The committee’s lawmakers spent hours debating dozens of amendments to the plan. Democratic lawmakers, who universally condemned the GOP’s budget instructions, tried to blow apart the resolution with poison pill amendments.

They accused Republicans of focusing the brunt of spending cuts on Medicaid, and offered a flurry of amendments to block them, but the GOP majority swatted them down.

Rep. Brandon Boyle, the top Democrat on the panel, offered an amendment to completely nix all of the resolution’s instructions, arguing that the hike to the debt limit and ceiling for tax cuts would blow “a hole in our deficit and our national debt.”

“Folks, they’re coming after your Medicaid, they’re coming after your healthcare, period, in order to pay for their large tax cuts for billionaires,” Mr. Boyle, Pennsylvania Democrat, said.

Mr. Arrington countered that any time lawmakers “try to reduce spending, find inefficiencies, it’s characterized as cutting somebody’s benefit.”

“So it scares everybody off, but I’m not scared, and my Republican colleagues aren’t scared,” he said.

Debt hawks in the House Freedom Caucus offered a tweak to the plan that would add a caveat to deeper spending cuts to the tune of $2 trillion. While the technical spending cut floor in the resolution would remain at $1.5 trillion, the new language incentivizes lawmakers to meet the higher benchmark.

If committees cut more than $2 trillion, tax writers can go further with tax cuts. But if they fall short of that line, then the Ways and Means Committee’s ceiling for tax cuts also falls.

Hitting $2 trillion exactly would leave the Ways and Means Committee’s $4.5 trillion net cost ceiling for sweeping tax cuts untouched.

“We want to make it deficit neutral,” House Freedom Caucus Chair Andy Harris, Maryland Republican, said. “We think that with our amendment, it ensures deficit neutrality, and that’s all we care about. Where they go for those cuts, that’s up to the committees.”

Advancing the budget blueprint through committee is the first step to passing Mr. Trump’s agenda. Next, committees will take up the more arduous task of piecing together policies that fit within the guardrails of the budget blueprint.

The House, however, is on a collision course with the Senate, which passed its budget resolution through committee Wednesday. Senate Republicans are not keen on waiting for their House colleagues, who are taking a weeklong recess next week.

Both chambers have to coalesce around one budget resolution to unlock the budget reconciliation powers that will allow them to ram Mr. Trump’s agenda through Congress without the threat of a filibuster by Senate Democrats.

Senate Budget Committee Chair Lindsey Graham, South Carolina Republican, wants his budget plan to be on the Senate floor for a vote next week.

Mr. Graham’s plan is more streamlined than what the House is offering, and adheres to the Senate GOP’s desire to split Mr. Trump’s agenda into two packages rather than cramming everything into one massive bill.

The Senate resolution calls for $345 billion in new border and defense spending that would be spread over four years, with other committees instructed to provide offsets over that same period.

Senate Majority Leader John Thune, South Dakota Republican, wouldn’t guarantee a floor vote next week.

“Stay tuned,” he said.

• Lindsey McPherson contributed to this report.

• Alex Miller can be reached at amiller@washingtontimes.com.