Ex-Labour minister Ian Austin has urged voters to back Boris Johnson at the general election.
Mr Austin, a former aide to Gordon Brown, said Jeremy Corbyn was "unfit to lead" because he was not a patriot and "always backs Britain’s enemies".
"You have got to stand up and you've got to tell the truth and do what's right. That is why I have decided the choice people have to make is to vote for Boris Johnson," he told talkRADIO.
Mr Austin said he was "really sorry" to his friends who were standing for Labour at the election, but insisted a Corbyn government would be a "disaster for Britain".
And he slated the party's "fantasy" Brexit policy, adding: "The idea that Jeremy Corbyn can negotiate a better deal so quickly... who takes that seriously?.
"If you go to the EU and negotiate a deal, then say I'm going to put it to a referendum, the EU are obviously not going to give you a deal that people will vote for because they want you to stay in."
The politician - who was adopted by Jewish parents - resigned from the Labour in February and became an independent MP after a long-running feud over antisemitism within the party.
He will not be standing in the upcoming election.
"They [Labour leadership] have allowed a political party with a proud history and a great track record of fighting for racism and standing up for equality to be poisoned with racism against Jewish people," he added.
"For me, it’s a fundamental issue. It's a red line. They have had years to deal with it. It has not been dealt with properly."
He continued: "I thought long and hard about this. I joined the Labour Party as a teenager, I was a councillor in my twenties, worked for the party in my thirties and became an MP and a minister in my forties. This has been my life."
Despite the comments, Labour's Rebecca Long-Bailey said Mr Austin would be welcome to rejoin the party.
"I don’t see that the bridges have been burned, as it were," she told talkRADIO.
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