WASHINGTON — It’s a make-or-break moment in House Speaker Paul Ryan’s crusade to pass the GOP’s Obamacare replacement amid growing opposition from critics in his own party who see a chance to not only topple the bill, but perhaps his young speakership as well.

No other Republican has staked his political capital on passage of the House GOP plan to repeal and replace the Affordable Care Act as much as Ryan. He’s hawked the plan almost daily on television and radio, including a wonkish PowerPoint demonstration, and worked furiously to drum up support in Congress and the White House.

“People say it’s like herding cats. It’s not herding cats. It’s herding ravenous tigers,” said Rep. Barry Loudermilk, R-Ga., a conservative who has yet to give his support to the House bill.

Whether the Wisconsin Republican can pull off the legislative lift as the bill heads to a House vote next week will establish not only Ryan’s power and legacy, but also the tone of his rocky relationship with President Donald Trump.

The House Budget Committee on Thursday narrowly voted to advance the bill to the House floor, 19-17, as some conservatives registered their opposition.

Three Republicans opposed the motion — Reps. Dave Brat of Virginia, Gary Palmer of Alabama and Mark Sanford of South Carolina — all of them members of the House Freedom Caucus, a group of hard-right lawmakers. All Democrats voted against the motion.

So far the White House appears only too happy to let Ryan carry the load of promoting the bill. Some of the president’s advisers have long been gunning to replace Ryan, and a misstep over the health care repeal bill could open the door.

On the other hand, success would cement Ryan’s reputation as a power broker and party leader.

But with opposition rising from both moderate Republicans and the hard-right House Freedom Caucus, Ryan’s best hope now seems to be amending his widely-panned bill in order to ensure at a minimum that it passes the House.

And if the House bill fails? “There’s going to be some damage control to be done,” Loudermilk said.

Conservatives balked at the bill they complain does not sufficiently repeal Obamacare. More traditional Republicans worried their constituents will be left without health care, particularly if the Medicaid provisions in the law are undone.

The last time Republicans were this divided — in 2015 — then-House Speaker John Boehner abruptly resigned.

Some of the attacks have started to get personal against Ryan and appear designed to drive a wedge into his already fraught relationship with Trump.

An initial whip count by GOP leaders was not expected to produce enough votes for passage.

And in a sign of the challenges he faces, Ryan now acknowledges that the bill will undergo “necessary refinements” to win broader support.

Conservatives are hopeful Ryan will adjust the bill with changes in their direction, perhaps by more quickly ending Obamacare’s expansion of Medicaid.

“He’s listening to everybody. He’s talking, much more open to ideas, in all fairness,” said Rep. Morgan Griffith, R-Va., who has yet to back the bill.

But pushing the bill rightward risks alienating more traditional Republicans who could withhold their votes or, as Minority Leader Nancy Pelosi said, “walk the plank” by voting for an unpopular bill that is dead on arrival in the Senate.

That would make passage in the House a symbolic victory for Ryan, but leave open the question of whether it was a substantive achievement.

In the Senate, Republicans are openly abandoning the bill, promising changes if it lands there.

At the White House with Trump and GOP senators this week, the chatter quickly turned to what some saw as the botched rollout, according to those familiar with the private meeting.

Even though Trump has vowed to campaign for the legislation, he devoted just a few minutes to it at a rally Wednesday in Nashville.

Democrats sense the president’s apprehension.

“President Trump has slapped his name on buildings, ties, steaks, hotels and golf clubs, but not on a bill that he says he supports,” said Senate Minority Leader Chuck Schumer, D-N.Y.,

The Washington Post contributed.

lisa.mascaro@latimes.com