The closer the Senate tax bill gets to a crucial up-or-down vote, the more Republicans are falling in line.

On Tuesday morning, Senator Bob Corker of Tennessee was threatening to oppose the proposal in a key Budget Committee vote because it might explode the deficit. Senator Ron Johnson of Wisconsin was warning he could do the same if party leaders didn’t address his complaints. By the afternoon, both wavering Republicans had provided the crucial “ayes” to send the $1.4 trillion tax cut to the Senate floor.

Then there was Senator Susan Collins, the Maine moderate who defied her party on each of its attempts to repeal the Affordable Care Act and was seen as likely to do so again on taxes. She had recited a litany of concerns with the bill, chief among them a provision scrapping Obamacare’s individual mandate—a change that she warned would cause rising premiums to spike even higher. But by the afternoon, after a party pep talk and a separate side session with President Trump, she, too, was nearing the “yes” column.

The Senate Republican tax overhaul still faces hurdles. Party leaders must keep their verbal commitments to the wavering senators, nail down the support of a few others, and ensure that the changes they’ve promised accord with the Senate’s complex budget rules. But Tuesday was undeniably a day of momentum for Trump and Republican congressional leaders, propelling them closer to enacting their long-sought tax cuts and ending a frustrating legislative slump. The full Senate could vote on the bill by the end of the week after a marathon session of floor debate and amendment votes.

“I think it’s going to pass, and it’s going to be very popular,” Trump said as he met at the White House with House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell.

Top Republicans were in whatever-it-takes mode on Tuesday, seemingly offering assurances to senators left and right as Trump met with the party in the Capitol. To win over Collins, the president reportedly said he was open to supporting bipartisan health-care legislation to restore the insurer payments under Obamacare that he cancelled earlier in the fall, along with a separate and potentially far costlier bill aimed at offsetting the impact of repealing the individual mandate.

Senate Republicans are also considering Collins’ push for the chamber’s bill to allow people to deduct up to $10,000 in state and local property taxes, which would bring the proposal in line with the House plan that passed earlier this month and make it easier for the two versions to be reconciled. “She’s had a number of good discussions with the White House, and they are continuing to negotiate in good faith,” a Collins aide told me. “She’s encouraged by the response to her proposals on the property tax deduction and on mitigating the impact of the repeal of the individual mandate.”

Corker told reporters after the party lunch that he had, according to the Washington Post, secured “a verbal agreement” for a trigger mechanism that would force tax rates to rise if the GOP’s rosy revenues projections miss their targets. If it comes together, that pact could also win the votes of Senator James Lankford of Oklahoma along with Senators Jeff Flake of Arizona and Jerry Moran of Kansas, who have all voiced similar concerns about the bill’s impact on the deficit.

Johnson was holding out for a different reason. He has pushed for more generous treatment of “pass-through” businesses like the one he ran in Wisconsin, arguing that the Senate proposal was much more favorable to big corporations. But he chose not to block the bill in the Budget Committee, another signal that a deal is in the offing which could bring along Senator Steve Daines of Montana as well.

Republicans can afford to lose no more than two of their 52 members to pass the tax bill without help from Democrats, none of whom are supporting the measure. But unlike their ill-fated tries on health care, not a single Republican has drawn a hard line against the tax proposal or issued demands that cannot, at least in concept, be met. Senator Rand Paul of Kentucky announced on Monday that he would back the tax bill despite his wishes that it would include even deeper cuts. “I don’t think anyone wants to be the one stopping this,” said Andy Roth, vice president of government affairs for Club for Growth, the conservative advocacy group.

In unifying around the tax bill, Republicans are setting aside polls showing it to be unpopular with the public, analyses finding that it benefits the wealthy at the expense of the lower and middle class, and their own acknowledgement that it will dramatically increase the deficit in the short term and likely beyond. But to an even greater degree than during the health care debate, the risk of another high-stakes failure is holding an otherwise divided party together. As Roth told me on Tuesday: “They know that they can’t strike out on this.”