Kevin McCarthy's gruelling bid to become speaker of the House of Representatives may finally be decided on the second anniversary of perhaps the most difficult day of his career.

On January 6, 2021, as a mob of Donald Trump's supporters stormed the US Capitol, the then-House minority leader and President Trump engaged in an angry phone conversation.

"You've got to call these people off," Mr McCarthy demanded of Mr Trump, according to Congresswoman Jamie Herrera-Beutler of Washington, whom Mr McCarthy told of the call. "They're your people."

"Well, Kevin, I guess they are just more upset about the election theft than you are," Mr Trump replied.

What followed, according to the congresswoman, was an exchange of obscenities.

Two years later, Mr McCarthy is back in the same halls of Congress ransacked by the mob, attempting - unsuccessfully for three full days - to win the speakership of the House of Representatives.

His circuitous journey to that point is part of the reason he is in such a precarious position today.

A week after the dust settled from the Capitol attack, Mr McCarthy took to the floor of the House to say Mr Trump "bears responsibility" for the violence and should have denounced it immediately. He said the attempt to disrupt the certification of Joe Biden's presidential victory was "undemocratic, un-American and criminal". While he did not support Mr Trump's impeachment, he backed a formal censure of the president.

Meanwhile, behind the scenes, he was telling Republican associates that he would urge the president to resign before his term expired later that month.

"I've had it with this guy," he would be recorded telling a group in a private phone conversation.

Fast forward just two weeks, and Mr McCarthy was travelling to Palm Beach, Florida, to meet with "this guy" in a show of support that seemingly contradicted his earlier public and private words.

"President Trump has agreed to work with Leader McCarthy on helping the Republican Party to become a majority in the House," read a statement from the former president that accompanied a photo of the two standing side by side in one of the oceanside club's palatial rooms.

In less than a month, Mr McCarthy had alienated Mr Trump's supporters by criticising their man and undercut attempts by Mr Trump's Republican opponents, including Senate leader Mitch McConnell, to put distance between the party and the former president.

This week, as Mr McCarthy was struggling to win over the handful of Republican holdouts who were blocking his ascent to the speakership, Mr Trump renewed his support for the man he once called "my Kevin". But it wasn't enough.

Despite the fact that many of the 20 Republicans blocking Mr McCarthy have been loyal Trump supporters, including some who voted to prevent certification of Mr Biden's victory in the hours after the Capitol attack, Mr Trump's endorsement had little sway.

"I disagree with Donald Trump," Congressman Ralph Norman, one of the holdouts, told the BBC. "He's backing Kevin McCarthy, and Kevin McCarthy is the one who said that he was going to censor the president - and the president should not have been censored."

One of the criticisms of Mr McCarthy, one that led Republicans to prevent his rise to the speakership in 2015 when he was next in line for the job after John Boehner's forced resignation, is that he has been insufficiently loyal to the conservative cause and too willing to bend to pressure. If that's the case, Mr McCarthy's efforts to placate his critics, to offer a range of concessions to win them over, may be only a further strike against him.

"Maybe the right person for the job of speaker of the House isn't someone who has sold shares of himself for more than a decade to get it," Florida Congressman Matt Gaetz, another of the Republican holdouts, said on Tuesday.

For some, Mr McCarthy's actions on January 6 two years ago - and in the days and months since - have only reinforced that view.