He can’t live with him and can’t live without him. But, finally, the conservative podcaster Tucker Carlson seems to have made up his mind about Donald Trump. Their up-and-down marriage of political convenience is heading for the divorce court.

On Tuesday Carlson admitted that he will be “tormented” for a long time by his support for Trump in the 2024 US presidential election “and I want to say I’m sorry for misleading people”. What he did not say is whether this presages his own run for president in 2028.

The breaking point was the war in Iran, a betrayal of Trump’s promise to end US foreign entanglements, and the perceived influence of Israel, which has become a Carlson obsession.

It was the latest – and perhaps final – twist in a long and tortured relationship. Back in 1999, when Trump was potentially running for president on a Reform party ticket, Carlson said he was “the single most repulsive person on the planet”. In 2016, he reportedly told an acquaintance that the Republican frontrunner was “not evil” but “mentally ill”.

He supported Trump against Hillary Clinton in that year’s election but managed to keep some daylight between himself and the Republican candidate and, by the summer of 2020, was expressing sharp criticisms. In 2021 he reportedly said of Trump: “I hate him passionately.”

Yet he was aligned on many issues and echoed Trump’s false claims that the 2020 election was stolen. After losing his perch on Fox News – the highest-rated cable news programme, described by the New York Times as “what may be the most racist show in the history of cable news” – Carlson went into podcasting and threw his weight behind the former president again.

He told the 2024 Republican National Convention in Milwaukee that Trump is “a wonderful person. I know him well. By the way, the funniest person I’ve ever met in my life, actually. You can’t be funny without perspective or without empathy, which is true.”

As recently as March, Carlson told the Status news site: “There are times I get annoyed with Trump, right now definitely included, but I’ll always love him no matter what he says about me.”

But by then the writing was on the wall. Trump had waged a war of choice in Iran. In the eyes of Carlson, fellow former Fox News host Megyn Kelly, ex-congresswoman Marjorie Taylor Greene and others, it was a fundamental betrayal of his “America first” ideology.

Carlson’s embrace of non-interventionism was forged by the disastrous Iraq war. He now contends that Trump had been unduly influenced by the Israeli prime minister, Benjamin Netanyahu, fitting a wider set of beliefs on the far right that all too often reek of antisemitism.

“He’s leaving Trump because he feels that Trump has not stayed true to the ideology he was ascribing to him,” says Jason Zengerle, author of a recent book, Hated By All the Right People: Tucker Carlson and the Unraveling of the Conservative Mind. “People like Tucker and Steve Bannon believe that the Maga movement is an ideological movement and that there are principles to it that Maga voters subscribe to independent of their love of Donald Trump.

“This is a great test of that. Is Maga a cult of personality or is it actually an ideological movement? I think it’s a cult of personality: most people who are Maga supporters will support whatever Donald Trump does. People like Bannon and Tucker think that there is an ideology there that these people are supporting and it’s not just Trump – and we’re about to find out.”

For years it has been speculated that Carlson himself might run for president some day. His denunciation of Trump on Monday, with its implicit assertion that Maga is bigger than any one man, could be a step in that direction.

Zengerle adds: “He’s not really a media figure at this point. He’s a movement leader. He thinks he’s leading a political movement and he thinks that movement has been betrayed by Donald Trump and so he’s trying to move it in a different direction away from Trump while keeping it consistent with his ideological beliefs.

“He’s positioning himself and his movement to pick up the pieces of what he thinks has been broken by Trump, positioning himself as the true heir – this person who has stayed true while everybody else has betrayed the faith.”

Asked how likely it is that Carlson will mount a White House bid, Zengerle laughs: “It’s a lot more likely than it was before.”