On January 13, a week before Donald Trump would take the oath of office and just days after the new session of Congress opened, Republicans in the House passed a budget resolution that was the first step, GOP leaders said, to repealing and replacing Obamacare. The bill passed, 227-198, with just nine Republicans defecting from the party-line effort.

Among those nine "no" votes were the two founding members of the House Freedom Caucus: Reps. Justin Amash (R-Michigan) and Rep. Raul Labrador (R-Idaho). Another "no" came from Rep. Thomas Massie (R-Kentucky), who isn't a member of the Freedom Caucus but shares many of the small-government, libertarian leanings of the group.

"We got a category five hurricane coming when you have to reduce to practice, the differences between Donald Trump's agenda and Paul Ryan's agenda," Massie told Roll Call after the vote. "I think there are going to be some very confusing votes in here."

How right he was. That January 13 vote was the first sign—a telling one, in retrospect—that the Freedom Caucus and other libertarian-leaning members of Congress (like Massie and Sen. Rand Paul of Kentucky) would become the biggest stumbling block to passing the House GOP healthcare plan. That bill is scheduled to receive a floor vote Thursday that, if the Republican leadership can cobble together the votes, would approve the American Health Care Act (AHCA) as part of that budget resolution that initially cleared the House on that Friday the 13th.

With the House vote on the AHCA looming on Thursday, Republican leaders can afford to lose 22 votes from their ranks. As of Wednesday evening, vote tallies tracked by various media outlets suggest anywhere from 23 to 29 Republican lawmakers intend to vote against the bill—enough to delay the vote or force significant changes to the bill. A significant number of those "no" votes come from Freedom Caucus members, including Reps. Dave Brat (R-Virginia), Mo Brooks (R-Alabama), Paul Gosar (R-Arizona), Jim Jordan (R-Ohio), and Mark Sanford (R-South Carolina), among others.

Freedom Caucus members have been skeptical of the AHCA almost since the moment it was publicly unveiled. "It's Obamacare in a different format," Jordan told The Atlantic on March 6, just shortly after Republican lawmakers got their first look at the proposal.

Amash was on the same page:

Though the Freedom Caucus never took an outright position on the bill, the handful of individual members who promised to vote against the bill have succeeded in at least complicating the Republican effort to get a majority. "I don't think there is any tinkering that will get us to 218," Labrador predicted in an interview with CNN.

There's still time for that to change, however, and House Republican leaders were reportedly considering substantial rewrites to the AHCA on Wednesday night. Depending on what changes, some of those expected "no" votes could swing to "yes" votes before the bill hits the floor.

Massie is less likely to be swung. On Wednesday, he tweeted a picture indicating that his vote had changed from "no" to "hell, no."

Sorry if I let you down. I'm changing my vote on #AHCA pic.twitter.com/JLUotqaO9L — Thomas Massie (@RepThomasMassie) March 22, 2017

Rep. Mark Meadows (R-North Carolina), chairman of the Freedom Caucus, told CNN on Wednesday that he was still a "no" and other members of the group promised to sink the bill even after meeting with President Donald Trump at the White House. By late Wednesday night, though, Meadows' resolve seemed to be wavering as conservative Republicans and the Trump White House continued to negotiate.

While obviously not a member of the House Freedom Caucus, Sen. Rand Paul (R-Kentucky) has been bird-dogging his like-minded colleagues in the lower chamber over the healthcare bill. He led reporters on a search for the bill, crossing from the Senate side of the Capitol to the basement room on the House side of the complex where it supposedly was being drafted. He was turned away at the door by a House GOP staffer.

After finally laying eyes on the bill a few days later, Paul didn't hold back. "This is Obamacare light. It will not pass. Conservatives are not going to take it," Paul told Fox & Friends. He said the bill would "do nothing" to bring health care costs down or to restrict the steady rise of premiums and took to Twitter to issue a beat-by-beat takedown of the proposal attacking it for keeping several elements of the Affordable Care Act intact, including subsidies for buying insurance (which would become a refundable tax credit in the House GOP plan) and the so-called "Cadillac Tax" on top notch insurance plans.

Paul will be central to the AHCA's prospects in the Senate—if it gets there. As of Thursday morning, it's impossible to say whether it will.

Opposition from conservative and libertarian-leaning Republicans in Congress has been bolstered by criticism from right-leaning and free market think tanks.

Michael Cannon, director of health care policy for the Cato Institute, said the proposal was "worse than Obamacare" when it was first introduced. Even after mild changes in the past week, Cannon on Tuesday was unmoved. "The amendments do not even come close to fixing the problems with this fatally flawed bill," he wrote. By expanding a provision that would replace Obamacare's health insurance subsidies with tax credits, Cannon said, "it will make the bill resemble Obamacare even more."

The Heritage Foundation has opposed the health care bill since it was introduced. Freedom Works, a conservative group with a direct line to the grassroots organizers that helped elect many of the Freedom Caucus members (and plenty of others) sent a letter this week calling for the bill's defeat. Club For Growth, which funds conservative campaigns, launched a $500,000 advertising effort this week targeting 10 moderate Republicans who have supported the health care bill.

Pushing a major entitlement reform through Congress without support from the liberty-minded crowd is no longer as easy as it once might have been.