WASHINGTON (AP) — Senators kept plugging through the night and into Saturday in contentious debate over a Republican budget plan that's central to President Donald Trump's agenda for trillions of dollars in tax breaks and boosts to border security and defense funds, all while slashing other government spending.

It could not have come at a more difficult political moment. The U.S. economy is churning over Trump's vast tariff scheme sent stocks plummeting, and experts are warning of soaring costs for consumers at home and threats of a potential recession. Even some Republicans have expressed concerns.

But GOP leaders with a nod from Trump are determined to march ahead, pushing past a hardened line of opposition from Democrats, who are unified against what they decry as tax breaks for the wealthy at the expense of federal programs Americans rely on. Approval, expected later Saturday morning, would pave the way for Republicans in coming months to muscle a tax cut bill through both chambers of Congress, just as they did in Trump’s first term.

“Let the voting begin," Senate Majority Leader John Thune, R-S.D., said Friday night.

The evening kicked off what's called vote-a-rama as Democrats were intent on making the effort as politically painful as possible, with votes on some 20 amendments to the package that GOP senators will have to defend before next year’s midterm elections.

Among them were proposals to ban tax breaks for the super-wealthy, end Trump's tariffs and clip his efforts to shrink the federal government. One, in response to the Trump national security team's use of Signal, sought to prohibit military officials from using any commercial messaging application to transmit war plans. Most were failing.

Democrats accused Republicans of laying the groundwork for increasing deficits and cutting key safety net programs such as Medicaid and nutritional assistance to help pay for tax cuts they say disproportionately benefit the rich.

“Trump's policies are a disaster," said Senate Democratic Leader Chuck Schumer of New York, as is Elon Musk's Department of Government Efficiency. “Republicans could snuff it out tonight, if they wanted.”

The Republicans frame their work as preventing a tax increase for most American families, arguing that unless Congress acts, the individual and estate tax cuts that Republicans passed in 2017 will expire at the end of this year.

The Senate package pulls in other GOP priorities — including $175 billion to bolster Trump's mass deportation effort, which is running short of cash, and another $175 billion for the Pentagon to build up the military — from an earlier budget effort.

Sen. John Barrasso, the No. 2 ranking GOP senator, said voters gave Republicans a mission and a mandate in November, and the Senate budget plan delivers.

“It fulfills our promises to secure the border, to rebuild our economy and to restore peace through strength,” Barrasso said.

Throughout the day, the debate was generally one-sided, as Democrats were taking full advantage of 25 hours of their available time, while Republicans yielded much of theirs to push ahead to the all-night voting frenzy. Pizza was wheeled in on a cart, for Republicans. Tacos, for Democrats.

Republicans use their majority to swat them back most amendments, often in rambunctious voice votes, though one GOP proposal to protect Medicare and Medicaid from cuts was adopted.

A few Democratic proposals, however, did draw some GOP support, including those to protect the Federal Emergency Management Agency and the bargaining rights of federal workers, backed by Sen. Susan Collins of Maine and Sen. Lisa Murkowski of Alaska, among others.

One Republican, Sen. Bill Cassidy of Louisiana, expressed his own misgivings about tax breaks adding to the federal deficits and said he has assurances that Trump officials would seek the cuts elsewhere.

“This vote isn’t taking place in a vacuum,” he said, a nod to the turmoil over Trump's tariffs.

And Republican Sen. Rand Paul of Kentucky, the lone GOP opponent to the plan so far, questioned the math being used by his colleagues that he said would pile on the debt load. “Something's fishy,” he said.

The House and Senate take different approaches that will eventually have to be resolved.

The House GOP budget plan provided for $4.5 trillion in tax breaks over 10 years, with some $2 trillion in savings pointed at changes to Medicaid, food stamps and other programs.

The Senate’s budget plan allows for extending the tax cuts under a scoring method that treats them as not adding to future deficits, even though a new estimate from the Joint Committee on Taxation projects they will add $5.5 trillion over the next decade when including interest, and $4.6 trillion not including interest.

On top of that, an additional $1.5 trillion in the senators plan would enable them to include some of Trump’s campaign promises, such as no taxes on tips, Social Security benefits and overtime. Republicans are also looking to increase the $10,000 deduction for state and local taxes, something that lawmakers from states such as New York, California and New Jersey say is necessary for their support.

The House and Senate are also at odds over increasing the debt limit, which is needed by summer to allow more borrowing. The House had boosted the debt limit by $4 trillion in its plan. But with Trump wanting the issue off the table, the Senate ups it to $5 trillion to push any further votes on the matter until after next year’s midterm elections.

The plan instructs four Senate committees to find at least $1 billion each in budget reductions. That's just a small fraction of the what's needed to offset the costs of the tax breaks. But GOP leadership emphasizes that's a low floor and that committees will be on the hunt for far more.

Already, the GOP leaders are confronting concerns from fiscal hawks in deep red states and congressional districts who want trillions of dollars in spending cuts to help pay for the tax breaks. At the same time, dozens of lawmakers in swing districts and states are worried about what those cuts will mean for their constituents, and for their reelection chances.

The GOP leadership has encouraged members to just get a budget plan over the finish line, saying they have time to work out the tough questions of which tax breaks and spending cuts to include.

Extending the the 2017 breaks would cut taxes for about three-quarters of households but raise them for about 10%. In 2027, about 45% of the benefit of all the tax cuts would go to those making roughly $450,000 or more, according to the Urban-Brookings Tax Policy Center, which analyzes tax issues.