WASHINGTON (AP) — President Donald Trump, the author of the best-selling book, "The Art of the Deal," is about to see his deal-making abilities ratified in a legislative showdown on the House floor — or dramatically rebuffed.

Trump, in a message relayed by White House officials, demanded that House Republican leaders vote Friday on a GOP-backed health care bill embraced by the president, placing the legislation on the brink of failure and jeopardizing his vow to repeal and replace former President Barack Obama's health care law.

By gambling on passing the major health care bill without the votes in hand, the former casino owner is staking the trajectory of his presidency on a roll of the dice, betting Republicans will go along rather than stand in the way of the long-sought repeal of "Obamacare." White House officials told lawmakers they would leave the health care law in place if the vote fails.

Trump's ultimatum came after House Republicans delayed a planned vote on the bill, a sign of possible defeat. In the weeks leading up to Thursday, Trump did his best to arm-twist resistant conservatives and moderates opposed to the legislation. He revived his campaign rallies to remind the voters, and their representatives, of the GOP's promises. He invited Republican lawmakers to the White House, having his advisers join them for bowling and pizza nights and cajoling them over the phone.

Famous for his lack of sleep, the president called lawmakers late into the night Wednesday in search of votes.

On Thursday, the president met with the hard-line House Freedom Caucus and the moderate Tuesday Group at the White House — but the lawmakers returned to Capitol Hill without a deal. Seeking a conclusion, Trump's budget director Mick Mulvaney told lawmakers it was time to vote and to move on.

Earlier in the day, Trump dismissed the deadlock as pure "politics." But, even allies noted, politics is his new business and he may still have a learning curve.

"I think he's probably discovering that the relationships on the Hill and the various groups are more challenging to negotiate than you would have thought and there's more history than he would have thought," said former House Speaker Newt Gingrich, a Trump supporter. "There are a lot of people who don't trust each other." Gingrich suggested that if the House was unable to win passage in the coming days, "then they have to take a deep breath and take a little longer."

To be certain, all aspiring presidents campaign on their ability to get things done, and many newly elected presidents later discover it's harder than it looks.

Still, the stakes for the president are high. Trump has referred to this health care legislation as the linchpin to an ambitious legislative agenda to overhaul the tax system and rebuild roads and bridges. A legislative defeat on health care only two months into his presidency would put into doubt his ability to win passage for those priorities and contradict the "Promises Made, Promises Kept" signs that have dotted his recent rallies.

It would also leave in disarray a young presidency already marked by a court challenges to a signature immigration policy, internal White House disputes, leaks, ethics questions and an FBI investigation into whether his campaign associates coordinated with the Russians leading up to the election.

Those aren't Trump's only troubles. He is negotiating with some lawmakers who have little incentive to cut a deal with an embattled president.

Several of the lawmakers in the House Freedom Caucus outperformed Trump in their deeply conservative districts, leaving them scant reason to worry about retribution in the next election.

Conservative organizations like FreedomWorks, Club for Growth, Americans for Prosperity, Heritage Action and Tea Party Patriots oppose the plan — frequently calling it "Obamacare lite" — even after the facetime with Trump. That gives conservatives the backup to go against the president even in congressional districts that Trump won overwhelmingly.

The White House has made concessions to conservatives, offering to amend the bill to axe key Obamacare provisions that guarantee insurance coverage of maternity care, mental health services, regular checkups and other essential health services.

In a sign of the tug-of-war that the bill has created within the party, the concessions pushed some moderates away. The future of the provisions remained fluid.

For a president who frequently holds grudges, Trump has yet to openly threaten dissenters with potential primary challenges. And only on Thursday did he use his massive Twitter feed to urge the public to pressure their members of Congress to back the plan.

The White House refused to entertain the possibility of failure. Even as Republican lawmakers prepared to cancel a Thursday vote on the legislation, Trump maintained that the bill still had a chance to pass the House. He told a meeting with trucking executives and drivers, "It's going to be a very close vote."

It wasn't the first time Trump has appeared somewhat distanced from the health care debate. He has, at times, skated over the details of the policy, promising a "terrific" health plan but veering away the particulars.

In a meeting with governors last month, the president appeared to express surprise about the system's complexity. "I have to tell you, it's an unbelievably complex subject," Trump said. "Nobody knew that health care could be so complicated."

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Associated Press Writer Ken Thomas has covered the White House and national politics for The Associated Press since 2011.

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Follow Ken Thomas at https://twitter.com/kthomasdc