WASHINGTON — (CNN) The buck now stops with Donald Trump.

The President on Tuesday fully embraced a House Republican plan to repeal Obamacare, shouldering a high-risk mission that holds huge implications for his own political future.

In the process, the one-time insurgent, who spent months blasting the Washington establishment, becomes the critical lever in making the GOP monopoly on power a vehicle to reshape the nation.

The unveiling of the Republican bill to dismantle the central pillar of President Barack Obama’s legacy was a significant moment in a new administration keen to make fundamental change.

But with conservative groups blasting the measure as “Obamacare Lite” and lawmakers like Sen. Rand Paul already warning it is “dead on arrival,” the White House was forced to send Trump to center stage to rescue the bill’s launch.

The idea of repealing Obamacare alone was once enough to unite the party, but differences on how to do it are beginning to tear at Hill Republicans.

Lawmakers are learning only political capital can drive big-ticket agenda items like health care reform into law. For a President who regards himself as the ultimate deal maker, the repeal of Obamacare represents a test of credibility after his campaign trail boasts about scoring big wins.

A legislative failure would not only enrage conservatives, it would cast doubt on the President’s ability to enact his own ambitious agenda.

It appears Trump recognizes the risks.

“There’s going to be no waiting, no more excuses by anybody, we’re going to get it done,” Trump told deputy Republican House whips at the White House during a brief appearance before reporters.

“I’m proud to support the replacement plan released by the House of Representatives. We’re going to have something much more understood and more popular than people can even imagine,” Trump said.

Privately, the President was even more explicit, warning the House GOP vote counters of the disastrous political consequences if they fail to corral sufficient votes.

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One source told CNN that Trump warned his guests that not passing a repeal bill could result in a “blood bath” for the party in mid-term elections in 2018.

“He said he hopes members understand that,” the source said, adding that as conservatives come to understand the consequences of failure, they will rethink their positions.

Trump is probably right on the first point. Fury over the GOP’s failure to block or repeal Obamacare helped ignite enthusiasm first under the tea party movement and then the Trump campaign. Failure with a Republican President in the White House would likely convince thousands of heartland GOP voters to stay home.

Back in Washington, Tuesday unfolded as one of the more orthodox days of the erratic Trump administration so far.

Instead of fighting firestorms over wild presidential tweets or feuding with the press, the White House mustered its forces for a prolonged push behind a key first 100 Days agenda item.

In a flurry of conventional political activity, a key Cabinet member — Health and Human Services Secretary Tom Price — appeared in the White House briefing room to promote the push. Vice President Mike Pence was on Capitol Hill, attempting to inject steel into Republican spines.

Trump himself will dine with Sen. Ted Cruz at the White House Wednesday, as part of an effort to woo conservatives who have yet to make up their mind on the bill.

The President’s engagement delighted Republican whips.

“President Trump has committed in our meeting that he is all in to making sure that this bill gets to his desk so he can sign it into law. And that’s really encouraging,” said Majority Whip Steve Scalise after meeting Trump.

His colleague Kevin Brady added: “The President made it very clear: This is his bill.”

But the President’s marching orders contrasted with some hostile early reviews for the draft law, underlining the immense political lift that is ahead.

On a day of crackling political action in Washington, it became clear that this effort will be just as painful and complicated as the previous large-scale attempts to remake health care in the Clinton and Obama administrations.

Passionate debates are already raging about costs and access, and on the fundamental question of how much responsibility government has to help its citizens access affordable health care.

But Trump’s attempt to make good on his campaign vows to provide “insurance for everybody,” lower deductibles and lower costs faces wider challenges than those perennial debates about health care policy.

To start with, almost no one seems to like the bill — even though Trump tweeted on Tuesday that it was “wonderful.”

Our wonderful new Healthcare Bill is now out for review and negotiation. ObamaCare is a complete and total disaster – is imploding fast!

— Donald J. Trump (@realDonaldTrump) March 7, 2017

Conservatives fault the plan to replace health subsidies with tax breaks as simply creating a new entitlement. They slammed Republican leaders for getting cold feet on a “clean repeal” now that they finally have a GOP President in the White House to sign an Obamacare repeal bill.

As Trump was meeting whips at the White House, conservative opponents of the bill gathered on a balmy March afternoon near the West Front of the Capitol Building to launch the resistance.

“We promised the American people we would drain the swamp and end business as usual in Washington. This bill does not do that,” Utah Republican Sen. Mike Lee said.

Conservative activist groups were also mobilizing to cause a headache for House Speaker Paul Ryan, whose political credibility is on the line.

“Many Americans seeking health insurance on the individual market will notice no significant difference between the Affordable Care Act (i.e., Obamacare) and the American Health Care Act. That is bad politics and, more importantly, bad policy,” said Heritage Action CEO Michael Needham.

Club for Growth President David McIntosh said the GOP plan fell far short of a free market solution to health care.

“If this warmed-over substitute for government-run health care remains unchanged, the Club for Growth will key vote against it,” he said.

Such conservative pressure could be important because especially in the Senate, Republican leaders cannot afford to lose significant GOP support to pass the repeal bill.

Disappointment with the bill meanwhile goes further than Washington conservatives.

Many Republican governors have criticized the plan because it does not preserve the long-term expansion of Medicaid introduced under Obamacare, putting the health plans of millions of Americans at risk.

“Phasing out Medicaid coverage without a viable alternative is counterproductive and unnecessarily puts at risk our ability to treat the drug addicted, mentally ill and working poor who now have access to a stable source of care,” said Ohio Gov. John Kasich in a statement.

The Medicaid issue could also be a stumbling block for the President since many of his Rust Belt blue-collar voters were able to access health care under the expansion.

But failure is not an option for Republicans. The days of passing satisfying but futile Obamacare repeal bills for a Democratic president to ignore are over.

“Obamacare has been a huge issue in four straight elections — 2010, 2012, 2014, 2016,” said Senate Majority Leader Mitch McConnell.

“The American people have given us an opportunity to govern. We’re no longer just floating ideas … we have an obligation now to the American people to deliver a replacement for Obamacare that is better than the status quo,” he said.

Democrats could tell their GOP colleagues a thing or to about the pain of passing a health care bill.

Many saw colleagues lose their jobs in the backlash to Obamacare. So they are relishing the chance to paint the House Republican bill as a “Reverse Robin Hood” bid to reward the wealthy and punish the poor, that would push millions of Americans off health plans.

No one believes that Democrats would line up to repeal the Obama’s proudest achievement.

But Trump will need Democratic votes in the Senate to pass stage two of the reform effort — framing a replacement for Obamacare, so the vehemence of the opposition party cannot be disregarded, at least in the long term.

Tuesday also produced the first gaffe of the health care saga when Republican Rep. Jason Chaffetz commented that lower-income people would have to make choices.

“So rather than getting that new iPhone that they just love and want to go spend hundreds of dollars on that, maybe they should invest in their own health care,” he told CNN’s Alisyn Camerota.

Chaffetz later walked back the comment, but his initial sentiments played into the Democratic claim that the bill would harm poorer people.

The flap was yet another sign that the task that Republicans have set themselves is unlikely to run smoothly.

“We are Republicans here, so we are not going to do this in a simple fashion and it won’t be without drama,” Republican Rep. Patrick McHenry told CNN’s Wolf Blitzer.

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