Sir Keir Starmer’s party rallied round “anti-Semitic” Azhar Ali despite mounting pressure on Labour to cut ties with the MP hopeful.
The Rochdale by-election candidate claimed Israel allowed the October 7 massacre to happen so it had cover to invade Gaza.
Labour frontbenchers joined Mr Ali at a campaign event and claimed he had been the victim of an online conspiracy theory.
But opponents said the candidate was “unfit” for office and called for him to be cut adrift from the party.
Firebrand rival for the seat George Galloway said Sir Keir is now caught in a “mousetrap” and predicted he will win the seat, which has a 9,000 Labour majority.
Speaking in Rochdale, he told the Daily Express: “There has been no apology ever given quite so craven and quite so insincere as the one he gave.
“This is a major league disaster for Keir Starmer because having been comprehensively beaten by us here in the Asian communities, he was counting on squeaking through with the support of white English people.
“And now those white English people are watching the news and following this big scandal which is now the biggest scandal in Britain.”
Mr Galloway, who is standing for the Workers Party of Britain, said Labour’s campaign is in “tatters” because it is too late for Sir Keir to choose a new candidate for the seat ahead of the February 29 vote.
He added: “So he’s damned if he does, he’s damned if he doesn’t. It is a classic mouse trap for him, there’s simply no way out of it.
“To be honest it doesn’t make much difference on the ground because I’m going to beat them anyway but the sensible thing for him to have done given all he’s done before is to immediately cut ties with the Labour candidate then at least his national problem would be less.”
Reform candidate Simon Danczuk, who used to be the town’s Labour, said Mr Ali only decided the comments were wrong “after he got caught out” and said his apology was “wholly inadequate”.
He added: “I think the Labour candidate should stand down and I think Labour should stop campaigning for him.
“What you effectively have now is Keir Starmer’s Labour trying to get an anti-Semite elected to Parliament, I think that’s absolutely appalling.”
He said the row is “damaging” democracy because Mr Ali cannot be taken off the ballot paper because the deadline has passed.
Shadow international development minister Lisa Nandy was pictured at campaign event on Monday.
Labour’s Nick Thomas-Symonds told broadcasters he believed that Mr Ali had fallen “for an online conspiracy theory.”
He said it would be “unfair” to draw a wider conclusion the Labour still has a problem with anti-Semitism.
Home Secretary James Cleverly said: “I’m not sure ‘Our candidate believed and repeated a vile and clearly antisemitic smear that he saw on the internet’ is quite the defence that Labour think it is.”
Conservative MP Paul Bristow said Mr Ali’s comments were “grossly offensive” and it was an “embarrassing situation” for Labour
He added: “If I were Sir Keir Starmer, I would make it clear that if this man should win that by-election he wouldn’t be a member of the Labour parliamentary party.”
Senior Tory Robert Jenrick said: “With Azhar Ali and Galloway both standing in the by-election in Rochdale, antisemitism is on the ballot.
“Both are totally unfit for office. Both will win thousands of votes. It’s a damning indictment of the political left and where we are as a country.”
