Senate begins debate on Trump's 'big, beautiful bill'

President Donald Trump celebrated the Senate's advancement of the "One Big Beautiful Bill" and acknowledged earlier holdouts -- Sens. Rick Scott, Ron Johnson, Mike Lee and Cynthia Lummis -- for casting their votes in favor of the bill in social media posts early Sunday.

"Tonight, we saw a GREAT VICTORY in the Senate with the 'GREAT, BIG, BEAUTIFUL BILL,' but, it wouldn't have happened without the Fantastic Work of Senator Rick Scott, Senator Mike Lee, Senator Ron Johnson and Senator Cynthia Lummis," Trump wrote.

"They, along with all of the other Republican Patriots who voted for the Bill, are people who genuinely love our Country!" he added.

In a second post, Trump wrote, "VERY PROUD OF THE REPUBLICAN PARTY TONIGHT. GOD BLESS YOU ALL!"

In a previous post late on Saturday night, Trump urged the Republican Party to unite and expressed frustration over "grandstanders."

"Republicans must remember that they are fighting against a very evil, corrupt and, in many ways, incompetent (Policywise!) group of people, who would rather see our Country "go down in flames" than do the right thing and, MAKE AMERICA GREAT AGAIN!" Trump wrote, suggesting that Democrats are more united.

"The one thing they do have is an ability to stick together, and vote as one group (They don't have GRANDSTANDERS!)," he continued.

-ABC News' Kelsey Walsh

After a bloc of four conservative "Big Beautiful Bill" holdouts finally voted late on Saturday night to move the legislation in a direction towards final passage, they claimed that negotiations with Republican leaders surrounding deficit reduction and Medicaid changes helped them feel "more comfortable" with its advancement.

"It was a beautiful night for the Big Beautiful Bill," Sen. Eric Schmitt, a key negotiator during meetings on Saturday, said after the vote.

Still, Sens. Ron Johnson -- who flipped his vote, Rick Scott, Cynthia Lummis and Mike Lee did not tell reporters whether they'd support the final bill, even after huddling with Senate Majority Leader John Thune, Vice President J.D. Vance, Majority Whip John Barrasso and some others during the over three hour vote.

Most of the four conservatives were tight-lipped about their negotiations with leadership after voting, but Johnson said that they were promised a vote on an amendment that would lower the Federal Medical Assistance Percentage match provided to able-bodied, childless people who are new enrollees to Medicaid expansion under the Affordable Care Act.

"We want to preserve Medicaid for disabled children," Johnson said. "I never had a problem with the House bill in terms of avoiding a massive tax increase, default funding for the border, for defense, the spending reductions they did get. My big beef there is…again, we still have to do so much more, because it's hard, okay, because it's such an enormous mess," he added, blaming years of Democratic policies like Obamacare.

Johnson said that the promised amendment was Scott's idea.

Lummis and Lee said that talks over their concerns about further deficit reductions and tax cuts help them get to a "yes" vote.

"We had an internal discussion about a strategy to achieve more savings, more deficit reduction," Lee said after the vote, adding that he's "more comfortable" now with the bill.

All agreed on the need for "as many tax cuts" and "as much spending clarity" as possible, Lummis said.

"I want to thank Vice President Vance for coming up and President Trump for his help in getting to yes, and we've got a good product, and we're going to promote it and pass it this week," she said.

-ABC News' Isabella Murray

The Senate voted to advance the "One Big Beautiful Bill," kicking off a lengthy process that GOP leadership hopes will end in its final passage.

For much of the night, it was believed that Vice President JD Vance would be required to cast a tie-breaking vote.

But at the last minute, Sen. Ron Johnson switched his no vote to a yes, giving Republican senators the votes they needed to advance the legislation.

Senate Democratic Leader Chuck Schumer also made official his request for the clerk to read the roughly 1,000 page bill in its entirely. She started at 11:08 p.m.

It could take her 15 hours to read every line, according to estimates.

Just because Senate Republicans mustered up the votes to get the process going doesn't mean they're in the clear.

There are a number of Republican senators who said they'd vote to advance the bill today but have not committed to casting a vote on final passage.

-ABC News' Allison Pecorin, Isabella Murray and Mariam Khan

The Senate floor is currently in a bit of a state of paralysis as Senate Republicans try to eke out the necessary votes to begin debate on the "One Big Beautiful Bill.'

The vote tally on the floor stands at 47-50. Three Republicans -- Sens. Mike Lee, Rick Scott and Cynthia Lummis -- still need to cast votes. All three of them will need to vote in favor of this bill in order to keep it moving forward.

The procedural vote on whether to begin debate on the bill has been open for nearly two hours. Vice President JD Vance arrived over an hour ago to prepare to cast the tie-breaking vote.

Even if Republicans get the necessary votes to proceed tonight, there's no guarantee they'll have enough votes when it comes to final passage. Some senators who cast votes to proceed tonight have been non-committal about how they'll vote on final passage.

-ABC News' Allison Pecorin