By LISA MASCARO, MARY CLARE JALONICK and MATT BROWN

WASHINGTON (AP) — The Senate slogged through a tense overnight session that dragged into Tuesday, with Republican leaders searching for ways to secure support for President Donald Trump’s big bill of tax breaks and spending cuts while fending off proposed amendments, mostly from Democrats trying to defeat the package.

An endgame appeared to be taking shape. Senate Majority Leader John Thune of South Dakota spent the night reaching for last-minute agreements between those in his party worried the bill’s reductions to Medicaid will leave millions without care and his most conservative flank, which wants even steeper cuts to hold down deficits ballooning with the tax cuts.

Vice President JD Vance arrived at the Capitol, on hand to break a tie vote if needed.

It’s a pivotal moment for the Republicans, who have control of Congress and are racing to wrap up work with just days to go before Trump’s holiday deadline Friday. The 940-page “One Big Beautiful Bill Act,” as it’s formally titled, has consumed Congress as its shared priority with the president.

At the same time House Speaker Mike Johnson has signaled more potential problems ahead, warning the Senate package could run into trouble when it is sent back to the House for a final round of voting, as skeptical lawmakers are being called back to Washington ahead of Trump’s Fourth of July deadline.

In a midnight social media post urging them on, Trump called the bill “perhaps the greatest and most important of its kind.” Vice President JD Vance summed up his own series of posts, simply imploring senators to “Pass the bill.”

What started as a routine, but laborious day of amendment voting, in a process called vote-a-rama, spiraled into an almost round-the-clock marathon as Republican leaders were buying time to shore up support.

The droning roll calls in the chamber belied the frenzied action to steady the bill. Grim-faced scenes played out on and off the Senate floor, and tempers flared.

The GOP leaders have no room to spare, with narrow majorities in both chambers. Thune can lose no more than three Republican senators, and already two — Sen. Thom Tillis of North Carolina, who warns people will lose access to Medicaid health care, and Sen. Rand Paul of Kentucky, who opposes raising the debt limit by $5 trillion — have indicated opposition.

Attention quickly turned to key senators, Lisa Murkowski of Alaska and Susan Collins of Maine, who have also wroked to stem the health care cuts, but also a loose coalition of four conservative GOP senators pushing for even steeper reductions.

Murkowski in particular was the subject of the GOP leadership’s attention, as Thune and others sat beside her in conversation.

Then all eyes were on Paul after he returned from a visit to Thune’s office with a stunning offer that could win his vote. He had suggested substantially lowering the debt ceiling, according to two people familiar with the private meeting and granted anonymity to discuss it.

And on social media, billionaire Elon Musk was again lashing out at Republicans as “the PORKY PIG PARTY!!” for including the $5 trillion debt limit provision, which is needed to allow continued borrowing to pay the bills.

Senate Democratic Leader Chuck Schumer of New York said his side was working to show “how awful this is.”

“Republicans are in shambles because they know the bill is so unpopular,” Schumer said as he walked the halls.

A new analysis from the nonpartisan Congressional Budget Office found 11.8 million more Americans would become uninsured by 2034 if the bill became law. The CBO said the package would increase the deficit by nearly $3.3 trillion over the decade.

Senators insisting on changes

Few Republicans appear fully satisfied as the final package emerges, in either the House or Senate.

Collins had proposed bolstering the $25 billion proposed rural hospital fund to $50 billion, offset with a higher tax rate on those earning more than $25 million a year, but her amendment failed.

And Murkowski was trying to secure provisions to spare people in her state from some food stamp cuts, which appeared to be accepted, while she was also working to beef up federal reimbursements to hospitals in Alaska and others states, that failed to comply with parliamentary rules.

“Radio silence,” Murkowski said when asked how she would vote.

At the same time, conservative Senate Republicans insisting on a vote on their plan for health care cuts, including Rick Scott of Florida, Mike Lee of Utah, Ron Johnson of Wisconsin and Cynthia Lummis of Wyoming, filed into Thune’s office for a near-midnight meeting.

A few of the amendments from Democrats were winning support from a few Republicans, though almost none were passing.

One amendment was overwhelmingly approved, 99-1. It would strip a provision barring states from regulating artificial intelligence if they receive certain federal funding.

What’s in the big bill

All told, the Senate bill includes $4.5 trillion in tax cuts, according to the latest CBO analysis, making permanent Trump’s 2017 rates, which would expire at the end of the year if Congress fails to act, while adding the new ones he campaigned on, including no taxes on tips.

The Senate package would roll back billions of dollars in green energy tax credits, which Democrats warn will wipe out wind and solar investments nationwide. It would impose $1.2 trillion in cuts, largely to Medicaid and food stamps, by imposing work requirements on able-bodied people, including some parents and older Americans, making sign-up eligibility more stringent and changing federal reimbursements to states.

Additionally, the bill would provide a $350 billion infusion for border and national security, including for deportations, some of it paid for with new fees charged to immigrants.

Democrats fighting all day and night

Unable to stop the march toward passage, the Democrats as the minority party in Congress are using the tools at their disposal to delay and drag out the process.

Democrats forced a full reading of the text, which took 16 hours, and they have a stream of amendments.

Sen. Patty Murray of Washington, the ranking Democrat on the Appropriations Committee, raised particular concern at the start of debate late Sunday about the accounting method being used by the Republicans, which says the tax breaks from Trump’s first term are now “current policy” and the cost of extending them should not be counted toward deficits.

She said that kind of “magic math” won’t fly with Americans trying to balance their own household books.

Associated Press writers Ali Swenson, Fatima Hussein, Michelle L. Price, Kevin Freking, Matt Brown, Seung Min Kim and Chris Megerian contributed to this report.