The Senate has kicked off “vote-a-rama” — the marathon of amendment votes on the Republicans’ domestic policy megabill.

The first vote wasn’t on adoption of a specific amendment, but instead on whether Republicans can use a controversial accounting tactic to zero out the $3.8 trillion cost of extending President Donald Trump’s 2017 tax cuts in their massive domestic policy bill.

Republicans assert that Budget Chair Lindsey Graham (R-S.C.) has the unilateral power to change the accounting method to the so-called current policy baseline. Yesterday, Senate Minority Leader Chuck Schumer moved to force a simple-majority vote on undoing the change; it’s expected to fail along party lines.

“Every senator will soon have an opportunity to reject this nonsense and vote for common-sense budgeting,” Schumer said on the floor Monday morning. “Americans will be watching.”

The vote has high stakes for Republicans because without the accounting change, Finance Committee provisions would increase the deficit by much more than the $1.5 trillion cap set out in the budget blueprint Senate Republicans adopted earlier this year.

Ahead of the voting, Senate Majority Leader John Thune underscored the need to address the expiring tax cuts: “This is about extending that tax relief, so the same people that benefited from it back in 2017 and for the last eight years don’t end up having a colossal, massive tax increase hitting them in the face come Jan. 1.”

The Senate will then move on to rapid-fire amendment votes from both Democrats and Republicans on curbing a key Medicaid funding mechanism, doubling the stabilization fund for rural hospitals to $50 billion, changing the bill’s artificial intelligence provisions and softening deep cuts to wind and solar energy.

“We will see, once and for all, if Republicans really meant all those nice things they’ve been saying about strengthening Medicare, about protecting middle class families, or if they were just lying,” Schumer said.

The votes are expected to go all day Monday and potentially into Tuesday morning. Vote-a-ramas are rarely held during daylight hours — majority-party leaders like to use fatigue as a weapon to bring things to a close — but Senate GOP leaders chose to give lawmakers a reprieve after multiple late nights.

CORRECTION: An earlier version of this story misstated Senate Minority Leader Chuck Schumer’s title.

The Senate’s “big, beautiful” vote-a-rama starts in just two hours — and nobody knows how it’s going to end.

Senate Majority Leader John Thune can only lose one more vote with Sens. Rand Paul (R-Ky.) and Thom Tillis (R-N.C.) already opposed. As Senate GOP leaders scramble to strike deals to keep the bill on track, House Republicans are drawing red lines, with fiscal hawks threatening to tank the bill over the Senate’s budget framework and moderates balking at the provider-tax crackdown.

Here are the big fights we’re watching when amendment votes kick off at 9 a.m., leading to a final vote on passage late Monday or early Tuesday:

Medicaid: GOP Sen. Rick Scott’s proposal to curb a key Medicaid funding mechanism after 2030 has Thune’s support as part of a deal struck to get the Florida senator and a handful of other holdouts to advance the megabill to debate.

If it fails, it could cost leadership some fiscal hawks, though Sens. Scott and Ron Johnson (R-Wis.) refused to go there Sunday night. If it passes, it could alienate so-called Medicaid moderates. One of them, Sen. Susan Collins of Maine, filed an amendment that would double the stabilization fund for rural hospitals to $50 billion, and pay for it by adding a 39.6-percent bracket on earners making over $25 million.

Medicaid moderates could also try to further water down the bill’s cut to the provider tax. Keep an eye on Tillis, now unburdened by a reelection bid, who slammed the Medicaid cuts in a fiery floor speech Sunday and might jump in again. Another key player to watch is Sen. Lisa Murkowski and whether her support slips after the parliamentarian derailed Medicaid-payment provisions aimed at winning over the Alaskan. The parliamentarian also, as of early this morning, had yet to rule on food-aid waivers for Alaska that could affect Murkowski’s vote.

Green credits: Moderates including Tillis and Sen. John Curtis (R-Utah) could offer amendments to soften the bill’s deep cuts against wind and solar energy, including its crackdown on IRA credits and a new excise tax. That could provoke a fight with House conservatives and the White House, which have pushed for aggressive rollbacks.

AI: Commerce Chair Sen. Ted Cruz (R-Texas) and Sen. Marsha Blackburn (R-Tenn.) are pitching a plan to cut the megabill’s 10-year moratorium on state enforcement of AI laws in half and make accommodations for internet protections.

The grand finale could be a manager’s amendment that House GOP leaders are pushing for to further resolve differences between the chambers and speed the bill to Trump by Friday. The House is scheduled to vote as soon as Wednesday at 9 a.m.

What else we’re watching:

— Farm bill fight: Dozens of agriculture groups are urging senators to oppose an amendment from Sen. Chuck Grassley (R-Iowa) that would limit income thresholds of farmers who can receive federal aid. A host of farm-state GOP senators also oppose Grassley’s push, according to three people granted anonymity. Some are concerned that liberal senators could join with conservative fiscal hawks to pass the amendment.

— Solar and wind tax backlash: The U.S. Chamber of Commerce and the Solar Energy Industry Association are slamming a new addition to the megabill that would tax solar and wind projects that have components from foreign sources, including China. “Taxing energy production is never good policy, whether oil & gas or, in this case, renewables,” Chamber executive vice president and chief policy officer Neil Bradley wrote on X.

— Campaign announcements: Rep. Don Bacon is expected to announce his retirement Monday, according to two people familiar with his plans. The centrist Republican’s Nebraska seat is a prime pickup opportunity for Democrats; it’s one of only three GOP-held districts Kamala Harris won in 2024. Meanwhile GOP Rep. Dusty Johnson is expected to announce a bid for South Dakota governor on Monday, according to two people familiar with his planning. He’ll be the eighth House Republican to run for higher office in 2026.

Jordain Carney, Meredith Lee Hill, Mohar Chatterjee and Josh Siegel contributed to this report.

Hours after announcing his retirement, Republican Sen. Thom Tillis went to the Senate floor and slammed the GOP’s plans for drastic Medicaid cuts — warning Republicans they are about to “make a mistake on health care and betray a promise” if their sprawling domestic policy bill passes.

“It is inescapable this bill will betray the promise Donald Trump made,” Tillis said. “I’m telling the president that you have been misinformed. You supporting the Senate mark will hurt people who are eligible and qualified for Medicaid.”

Tillis, who opposed the bill on a procedural vote Saturday night and then announced Sunday he would not seek reelection, said he could not vote for the Senate’s bill because of provisions that he said would kick some 663,000 residents of his state off their health care plans. He called on the Senate GOP to jettison its “artificial” July 4 deadline and rewrite the bill.

“I respect President Trump, I support the majority of his agenda, but I don’t bow to anybody when the people of North Carolina are at risk, and this puts them at risk,” Tillis told reporters after he left the floor.

The two-term senator who has been known for working across the aisle said he had done his own research on how changes to so-called state directed payments and a new cap on medical providers taxes would affect his state — contacting state legislative leaders, the state’s Democratic governor, Josh Stein and hospital groups.

Tillis said he also talked to CMS Director Mehmet Oz and presented his findings that showed the best-case scenario was a $26 billion cut in federal support.

“After three different attempts for them to discredit our estimates, the day before yesterday they admitted that we were right,” Tillis said on the floor. “They can’t find a hole in my estimate.”

In his remarks to reporters, he said Trump is “getting a lot of advice from people who have never governed and all they’ve done is written white papers,” adding that he has “people from an ivory tower driving him into a box canyon.”

Tillis, who was elected to the Senate in 2014, compared Trump’s “big, beautiful bill” to the Affordable Care Act: “The effect of this bill is to break a promise. And you know, the last time I saw a promise broken around health care, with respect to my friends on the other side of the aisle is when somebody said, ‘If you like your health care, you can keep it.’”

The Senate is now working through up to 20 hours of debate, before a marathon voting series of amendments scheduled to start Monday morning. Tillis said he might return to the floor to speak against the bill.

Trump lambasted Tillis Saturday night after he voted against opening debate on the megabill, and Tillis said he’d already told Trump at that point he was likely to retire.

“Pretty much what I said on the floor is what I said to the president last night and I stand by it,” Tillis told reporters after the speech, adding later that he told the President he “probably needed to start looking for a replacement.”

“I told him I want to help him,” Tillis added. “I hope that we get a good candidate that I can help and we can have a successful 2026.”