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

A fiery Sen. Thom Tillis, R-N.C., took to the Senate floor on Sunday evening to explain his vote from Saturday against the motion to proceed on the One Big Beautiful Bill Act, condemning the legislation and saying it breaks President Donald Trump’s promises to protect Medicaid.

“What do I tell 663,000 people in two years, three years, when President Trump breaks his promise by pushing them off of Medicaid because the funding is not there anymore, guys?” Tillis asked at one point.

“The people in the White House advising the president, they're not telling him that the effect of this bill is to break a promise.”

Tillis, who had earlier on Sunday announced his plans to retire from the Senate following attacks from Trump over his decision to oppose the GOP megabill, also said that the president’s self-imposed July 4th deadline to pass the legislation was “artificial.”

“I believe that we can make sure that we do not break the promise of Donald J Trump– that he's made to the people on Medicaid today,” Tillis continued. “But what we're doing because we've got a view on an artificial deadline on July 4 that means nothing but another date and time we could take the time to get this right, if we lay down the house mark of the Medicaid bill and fix it."

"What’s wrong with actually understanding what this bill does?" the senator asked.

-ABC News' Isabella Murray

As the Senate officially began debating the "big beautiful bill," President Donald Trump took to his social media platform on Sunday, advising Republican senators not to "go too crazy!" and suggesting that they still need to be reelected.

"For all cost cutting Republicans, of which I am one, REMEMBER, you still have to get reelected," Trump wrote on Truth Social. "Don’t go too crazy! We will make it all up, times 10, with GROWTH, more than ever before," he added.

The president's comments come as a number of Republican senators who voted to advance the bill on Saturday said they are still considering how they'll vote on its final passage.

-ABC News' Kelsey Walsh

After a dramatic procedural vote late Saturday night and a nearly 16-hour reading of the bill, the Senate started debate on Trump’s megabill.

There can be up to 20 hours of debate, but not all of it is expected to be used. It’s likely that Democrats will use all or most of their allotted 10 hours and Republicans won’t use all of theirs.

After debate on the bill, which is likely to conclude in the wee hours of Monday morning, a vote-a-rama will begin. It's unclear how long that might go, but upon its conclusion the Senate will vote on final passage of the bill.

Still, the bill’s final passage is not certain.

A number of Republican senators who voted to advance the bill on Saturday said they are still considering how they'll vote on its final passage.

Shaky Republican support for the package got even more unstable overnight, with the Congressional Budget Office releasing its estimate that the Senate's version of the bill would add $3.3 trillion to the nation's debt over the next decade.

And the Senate parliamentarian ruled overnight that several provisions in the bill were out of order under reconciliation, including a provision that would boost the federal share of Medicaid for “high-poverty” states of Alaska and Hawaii -- a portion of the bill that was a bright spot for Sen. Lisa Murkowski, a moderate Republican holdout who has been critical of the legislation’s deep cuts to Medicaid and the Supplemental Nutrition Assistance Program.

-ABC News’ Isabella Murray

The Senate's version of Trump's mega policy bill would add $3.3 trillion to the nation's debt over the next decade, according to the latest estimates released by the nonpartisan Congressional Budget Office on Sunday.

This latest estimate is roughly $1 trillion higher than the CBO’s score of the House's version of the bill, which it estimated would add roughly $2.4 trillion to the deficit over the next decade.

Additionally, the Senate's bill could also result in even more people losing their health care due to the cuts to Medicaid and additional cuts to the Affordable Care Act -- with roughly 11.8 million people potentially on the chopping block. The CBO estimated 10.8 million people could become uninsured over the next decade in its score of the House version of the bill.

The Senate's bill is expected to make deeper cuts to Medicaid due to new work requirements, but also due to steeper taxes that will be placed on some health care providers and hospitals to help cover the cost of Medicaid, known as the provider tax.

Republicans have argued in recent weeks that the CBO analysis is not accurate and they have been highly critical of the nonpartisan office.

-ABC News’ Mariam Khan