Republicans are trying to get their plan to overhaul the US tax system through the US Senate this week, but with 52 members in the chamber, GOP leaders can afford to lose only two votes.
As the bill heads to the Senate floor, a small group of Republicans have yet to show their full support for the bill, and Republicans are scrambling behind the scenes to reach just the right agreement that would get to 50 votes.
Leadership made progress Wednesday afternoon when Sen. Steve Daines of Montana, one of only two Republicans who had expressed outright opposition to the bill, came around after negotiations involving the pass-through business rate.
"I've seen enough progress to vote yes to move the debate forward," he tweeted Wednesday.
Republicans cleared a big hurdle earlier this week when the Senate Budget Committee approved the bill -- a move that was uncertain down to the last minute since Republicans weren't sure they had the 12 committee votes they needed.
Here's where key Republicans stand:
Sen. Ron Johnson of Wisconsin
Until Tuesday afternoon, it was unclear whether Johnson would vote for the bill to clear the budget committee, where Republicans hold just a one-vote majority.
To the delight of his Republican colleagues, he ultimately voted in favor of the bill, and the committee approved it along a party line vote, 12-11. He also voted "yes" Wednesday night on a procedural vote to move the bill forward on the floor.
"We need to make some progress," Johnson told CNN when asked if he'd commit to voting for the final bill.
Johnson was the first GOP senator to say he'd vote against the plan. His concerns have surrounded the tax rate for business entities that pass through their earnings to the individual side.
Sen. Bob Corker of Tennessee
Corker, who's had serious concerns about increasing the debt, also voted for the bill in committee.
Worried, however, that it could fail to generate enough growth to pay for itself, Corker hopes to include a measure that would trigger a way to offset the costs.
Corker has been in meetings this week and said he feels optimistic about a deal, though he has not elaborated on the contours of any agreement.
"Hopefully it's going to be memorialized and part of the bill. I haven't voted for a piece of legislation yet that I thought was just outstanding," he said Wednesday. "Well, maybe. But not many."
Sen. John McCain of Arizona
As of Wednesday, McCain said he still hadn't made up his mind on the proposal, repeatedly telling reporters on Capitol Hill, "I haven't decided yet." Earlier this week, McCain applauded the Senate Finance Committee for passing the bill through "regular order" before Thanksgiving. On Monday, McCain complained that the bill was changing too frequently. When asked by reporters if he liked the process, he said, "Oh, I don't know. It changes every day."
Sen. James Lankford of Oklahoma
Lankford also believes the Senate bill needs to include a backup plan to pay for it in case the economic-growth projections conservatives are banking on don't materialize.
He said he is deeply concerned about the impact of the tax bill on the federal debt and budget deficits, especially if the 0.4% growth projections anticipated by the tax changes don't hold up. He is working with GOP leadership and members of the Senate Finance Committee to craft a "what if" plan in case they don't.
"So, yes, I am on board with this bill because I want to see the good economic growth that's coming with it, but I also want to make sure we're protecting future taxpayers with debt and deficit," he said Wednesday on Fox News.
Sen. Susan Collins of Maine
While Collins was previously considered a likely "no," she has shown a great degree of openness in the past two days on Capitol Hill. That's in part because she said she's gotten some support from the President himself for some of her proposed changes, including provisions that bolster the Obamacare marketplace.
When a reported noted Tuesday that she seemed much more supportive of the bill, Collins said "that is a fair assessment."
"A lot of my concerns it appears are going to be addressed," she added. "I'm going to be given the opportunity to offer amendments on the Senate floor."
Sen. Jeff Flake of Arizona
Like Corker, Flake is also worried about exploding the debt with the new tax reform plan. Flake has cited some of the changes that affect the middle class but disappear after a specific period as another one of his issues.
"We're still working on, you know, the deficit issues. That's my big concern," he said Tuesday. "So I think there's some progress to be made."
Sen. Marco Rubio of Florida
Rubio told reporters on Monday that he hasn't decided how he'll vote, saying there's still "not enough" progress in making child tax credits refundable for payroll workers. He's proposing an amendment with Sen. Mike Lee, R-Utah, that would make that fix, and they suggest raising the proposed corporate rate from 20% to 22% to pay for it.
The White House, however, expressed opposition to the proposal on Wednesday.
"We think that it's important to make businesses more competitive. We would not support raising the corporate rate as outlined in that amendment," principal deputy press secretary Raj Shah told reporters.
This story has been updated and will continue to update with additional developments.