Donald Trump was elected in large part on one, loud promise: I know how to make deals these normal politicians don't.

Part of that mystique — as outlined in his best-selling book “The Art of the Deal” — is the willingness to call his rival's bluff, to put his cards on the table and ask everyone else to do the same.

That's what Trump did Thursday night after a postponement of the planned vote to begin the process of reforming the Affordable Care Act. House Republicans needed to put up or shut up, Trump insisted. Despite being told the votes simply weren't there, Trump pushed forward — arguing that it was now or never.

It was vintage Trump, taking a gamble no other typical politician would take: Force a vote on a massive part of your legislative agenda with an uncertain outcome.

Then Trump blinked.

Hours after Trump huddled with Speaker Paul D. Ryan at the White House, he told The Post's Bob Costa that he had decided congressional Republicans should pull the legislation. The votes simply weren't there, and the possibility of real embarrassment on the House floor existed.

Sure. But, Trump was elected as an outsider — someone who ran against the system. Why not force that system to go on the record with either their support or opposition?

Now begins the blame game. And there's plenty to go around. The White House was already starting to point the finger at Ryan for making health-care reform the first legislative priority of the new Republican-controlled Washington. Rank and file members were suggesting that simply not enough time was given to thinking about what was in the bill before it was offered. Establishment Republicans blamed the House Freedom Caucus for their refusal to compromise.

"We're going to be living with Obamacare for the foreseeable future," he said.

All true! But Trump is the president of the United States. Trump ran as the only person who could solve the major problems facing the country. Trump was the one who billed himself as the dealmaker extraordinaire, the guy who had faced down people in corporate boardrooms all over the country and all over the world — and won.

But when the time came to push all his chips to the middle of the table, Trump folded. Period. Beyond the spin, that is what happened here. If Trump had continued to insist that the bill be put to a vote, trust me that Ryan would have done it despite his reservations.

What you are likely to hear over the next few hours and days is that Trump did so because no deal is better than a bad deal. The problem with that argument is Trump's Twitter paper trail. Friday, as the House prepared to vote, Trump tweeted that this legislation was a great chance for Republicans to make good on their campaign promises — calling the legislation a “great plan.”

Trump will, as he always does, somehow declare victory and move on. “The beauty,” Trump told Costa, “is that they [Democrats] own Obamacare. So when it explodes, they come to us, and we make one beautiful deal for the people.”

The simple fact, however, is that Trump wanted this deal, pushed for this deal, called his own party's bluff on this deal and then walked away when it appeared as though the deal wouldn't come together.

Dealmaker Donald played chicken. But he lost his nerve at the last minute.