Former Congressman Adam Kinzinger, a Republican and vocal critic of Donald Trump, said some family members disowned him for pushing back against the former president.
He said his angry relatives believed he was a part of the "devil's army."
“So, I had family that sent a certified letter disowning me,” Mr Kinzinger told CNN's Anderson Cooper. “They said I’ve lost the trust of great men like Sean Hannity, which is funny, but they believe that. They said I was a member of the devil’s army."
Mr Kinzinger served in Congress between 2011 and 2023. He frequently criticised Mr Trump's claims that the 2020 election had been stolen, and was among the voices calling for the former president to be removed from the White House following the Capitol riot in 2021. He also sat on the House select committee which investigated the events of 6 January, 2021.
The discussion was held ahead of the release of his new book, Renegade, which reflects on his life and his time in politics.
The book includes his belief that the US political system is broken, and on his growing disillusionment with the Republican Party, according to NPR.
During an interview with the broadcaster, Mr Kinzinger said he believes people are seeking public office "to become famous" rather than because they believe they can make the country better through proper governance.
He said other, more traditional members of the Republican Party have responded to the influx of MAGA lawmakers by putting "their head in the sand" and pretending "like we can get this fixed by just allowing the far right to have their way."
The former congressman also spoke on the recent debacle in the House following the ousting of former House Speaker Kevin McCarthy. He said he was not surprised that the "terrorist caucus" — citing former Speaker John Boehner's term for hard-right Republicans in the House — managed to force the vote and hold the chamber hostage, but also showed no sympathy for Mr McCarthy, saying it "couldn't happen to a nicer guy."
He said despite all the bad blood, the disillusionment, and the rancour from his family, he still considers himself a Republican.
"I do, only because I'm not willing to give up and only because I haven't changed. I will say I will call myself a Republican that feels politically homeless at the moment and don't know where I belong," he told NPR.
That said, he may not vote Republican in 2024, especially if Mr Trump heads the ticket.
"But I also know that if everything kind of tracks the way it is in 2024, I won't be voting Republican because, again, I think it's a simple question of democracy or no democracy," he said. "And the Republican Party represents right now a real slide to authoritarianism ... If it was Joe Biden and Donald Trump, I don't think there's any question I would vote for Joe Biden."