Senate Majority Leader Mitch McConnell appears poised to push his members to get in line but there is a wide array of factions to satisfy and McConnell can only afford for two of his members to peel off. If three revolt, the GOP's plans of repealing the Affordable Care Act are dashed and valuable time in President Donald Trump's first 100 days will have been wasted.
Senate leaders are already praising the bill, but its unclear if that will be enough.
"I think it's a monumental shift from Obamacare and that's what we need to do," said Sen. John Barrasso, R-Wyoming, a key player in the health care debate.
But already, Sen. Rand Paul, the junior Republican from Kentucky, has blasted the House's bill calling it "Obamacare lite" and Sen. Mike Lee, a conservative member from Utah, called the House's plan to repeal the Affordable Care Act a "missed opportunity" in a statement Tuesday.
"This is not the Obamacare repeal bill we've been waiting for. It is a missed opportunity and a step in the wrong direction," Lee said. "We promised the American people we would drain the swamp and end business as usual in Washington. This bill does not do that."
That is two. McConnell can only afford to lose one more.
Paul and Lee are expected to speak at a news conference at the Capitol Tuesday afternoon, where they will appear with members of the House Freedom Caucus who also have their own concerns about the bill's refundable tax credits.
"We don't know how many people would use this new tax credit, we don't know how much it will cost, and we don't know if this bill will make health care more affordable for Americans," Lee said.
The pressure is only mounting for conservatives on Capitol Hill to reject the House's version of Obamacare repeal. So far three conservative groups -- Heritage, Club for Growth and FreedomWorks -- have blasted the legislation. But some noteworthy conservatives are holding their fire for now.
In an interview with reporters Tuesday, Texas Sen. Ted Cruz -- who has been pushing leadership to bring up the 2015 Senate repeal bill for a vote -- said he hasn't made a decision on the bill at this point.
"I have been vocal in expressing my concerns about how we should approach repealing Obamacare, that we should start with the 2015 repeal language as the bare minimum and build up from there," Cruz said. "I am still studying the details of the bill. It was released yesterday evening, but I am working closely with members of the House, members of the Senate and the administration to pass a repeal bill that honors our commitment to repeal Obamacare, that lowers cost, that expands access and choices and patient control over your own health care."
Conservatives aren't the only members McConnell will have to keep an eye on, however. Moderate members from states that expanded Medicaid under the Affordable Care Act are also still trying to make up their minds about the House's bill. The House bill gave Medicaid-expanding states more protection than some expected, but it is not clear it will be enough to satisfy senators who have pledged not to vote for any bill that would take coverage away from those who have it now.
Alaska Republican Sen. Lisa Murkowski, whose state expanded Medicaid, told reporters Tuesday that she still hadn't read the the House's bill nor had she been briefed on it. As reporters surrounded her, Murkowski jokingly begged a reporter who was asking about an unrelated topic to "keep talking please" so she could avoid the health care questions awaiting her.
"I'm talking about energy because, you know what? I haven't read the House bill. I confess," Murkowski said. "As far as I know, I don't know because what I want to do is actually get to my office this morning and talk to my health folks."
A group of tourists walked by and Murkowski humorously reached out to them to "please come out into this scrum."
It's not only Medicaid expansion funding that Murkowski has had concerns about. In the past, Murkowski also has expressed frustration that the House bill would include a defunding of Planned Parenthood.
"I don't think that the Planned Parenthood defund should be in the ACA bill that we're dealing with. Just don't think so," she said.
Sen. Jeff Flake, a Republican from Arizona, also confessed he hadn't made up his mind yet and was still working through the bill.
"Negotiations are tough enough without commenting before I understand it all," Flake said. "We've got a small margin. You know the numbers. It's tough."
In an effort to build consensus, Flake said that Vice President Mike Pence was planning to huddle with Republicans at their lunch.