WASHINGTON — The Senate’s long day of voting churned toward evening Monday, with Republican leaders grasping for ways to shore up support for President Donald Trump’s big bill of tax breaks and spending cuts while fending off proposed amendments from Democrats who oppose the package and are trying to defeat it.

The outcome was not yet in sight. Senate Majority Leader John Thune of South Dakota acknowledged the Republicans are “figuring out how to get to the end game.”

And House Speaker Mike Johnson signaled the potential problems the Senate package could face when it is eventually sent back to his chamber for a final round of voting, which was expected later this week, ahead of Trump’s Fourth of July deadline.

“I have prevailed upon my Senate colleagues to please, please, please keep it as close to the House product as possible,” said Johnson, the Louisiana Republican, as he left the Capitol around dinnertime. House Republicans had already passed their version last month.

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.

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 — have indicated opposition. Tillis abruptly announced over the weekend he would not seek reelection after Trump threated to campaign against him.

Ahead of Monday’s voting Senate Democratic Leader Chuck Schumer of New York said the “hardest choices” for Republicans are still to come.

“With every rewrite Senate Republicans have made their bill more extreme,” Schumer said. “All to give tax breaks to billionaires.”

Democrats have proposed dozens of amendments in what’s called a vote-a-rama, though most are expected to fail. Democrats are united against the Republican president’s legislation and eagerly lined up to challenge it.

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.

The White House said it was counting on Republican lawmakers to “get the job done.”