WATCH: Why President Trump Couldn’t Close the Deal on Obamacare Repeal

It was early in his tenure as the 45th president of the United States, and Donald Trump wanted a win.

For seven years, the Republican Party had decried the passage of the Affordable Care Act, and President Trump had made repealing and replacing “Obamacare” a key campaign promise. With Republicans in control of the House, the Senate and the White House, the time seemed right to act.

But as the above excerpt from Trump’s Takeover — a new FRONTLINE documentary chronicling the president’s relationship with the GOP during his first year in office — explores, divisions between Speaker Paul Ryan’s wing of the party and the more conservative Freedom Caucus made drafting a repeal bill that could pass the House a difficult task.

Enter Trump, who thought he could bridge the gap using his skills as a salesman.

“That’s the businessman in him — that he understands the backslap, the Oval Office lunch, the Air Force One ride, that personal attention, those relationships can largely help pull one or two votes or make a lasting friend,” former White House Press Secretary Sean Spicer tells FRONTLINE.

There was a problem, though. As the FRONTLINE documentary reports, the president didn’t seem to understand or care about the details of the bill he was selling.

“The president was not particularly engaged in the policy details. That was pretty apparent,” Rep. Charlie Dent (R-Penn.) tells FRONTLINE. “The president seemed to defer to Congress, largely, and basically, ‘Whatever you guys pass, I’ll sign.’”

With the Freedom Caucus holding out, the president issued an ultimatum: vote yes, or he would walk away from the bill. When the caucus refused to get on board and Ryan delivered the news to Trump, the president called Robert Costa of The Washington Post — taking his own party to task.

“’I don’t need this broken Republican Party,’ he said, ‘if they’re not going to really help me, if they’re not going to get their stuff together,’” Costa tells FRONTLINE of the phone call. “What he really wanted was a win. He wasn’t pushing for an ideological win. He wasn’t pushing for a political win. He wanted a win for Donald Trump, and the Republican Party failed him.”

It was the president’s first big legislative test, and a key early moment in his relationship with the GOP-led Congress. And since then, as the film explores, Trump has worked to remake the party in his own image, counterpunching when criticized, publicly attacking Republicans who defy him — and meeting with relatively little resistance.

“Somebody needs to stand up and say, ‘This is not our party. This is not behavior that we should condone. We shouldn’t be OK with this. This is not normal,’” Senator Jeff Flake (R-Ariz.), one of the few legislators in his party to proclaim this point of view so publicly, tells FRONTLINE.

From Trump’s attacks on party leaders on Twitter after the repeal-and-replace bill died, to a split over what many in the party said was the president’s inadequate response to deadly violence at a white supremacist rally in Charlottesville, to when Congress ultimately delivered a major legislative victory for Trump with the passage of tax reform, the documentary traces the president’s takeover of the party, from the perspective of Republican lawmakers.

“What the Republican establishment now know is Donald Trump is unequivocally the leader of the Republican Party,” former Trump campaign manager Corey Lewandowski tells FRONTLINE.  “He is the one who sets the tone of what takes place in Washington.”

From Michael Kirk and the team behind Putin’s Revenge, Divided States of America and The Choice 2016, Trump’s Takeover is a gripping and revealing window into the potential lasting impact of the Trump era on the Republican Party and U.S. politics as a whole.

Trump’s Takeover  premieres Tuesday, April 10 at 10 p.m. EST/9 p.m. CST on PBS and online.