Video report by ITV News Political Correspondent Romilly Weeks
Jeremy Corbyn's bid for Number 10 has suffered a series of blows as two former Labour MPs urged voters to back Boris Johnson instead at the General Election.
Ian Austin said the Labour leader was "not fit to lead", and was joined by John Woodcock as they launched a campaign labelling Mr Corbyn a "disgrace to his party".
Mr Austin, who served as Gordon Brown's press secretary, said Jeremy Corbyn was "completely unfit" to become prime minister. He cited Labour's alleged lack of action in dealing with anti-semitism in the party as proof he was unfit to govern the country.
Mr Austin told ITV News: "It's the hardest decision I've ever had to make but I've got to tell people the truth, and the truth is only two people can be prime minister on December 13: Jeremy Corbyn or Boris Johnson.
"I think that Jeremy Corbyn is completely unfit to lead our country and that's why I think people... have got to vote for Boris Johnson and make sure Jeremy Corbyn gets nowhere near Downing Street."
He added: "This election is not a foregone conclusion. If Boris Johnson doesn't get an overall majority then I think Jeremy Corbyn will be in Number 10.
"I think that's too big a risk for the country. I don't want to see what these people have done to the Labour Party do what they did to the country. I think it would be a disaster."
Mr Austin said he would not stand for re-election in his Dudley North, which he has held since 2005, over fears it could take votes off the Conservative candidate and help Labour win the seat.
Mr Woodcock, who announced this week that he would not stand for re-election in Barrow and Furness, told ITV News: "I understand a lot of my friends who are still in the Labour Party are saying you can't say vote Tory and I've been bought up like that as well.
"Although this isn't the choice any of us would have wanted to make, it's the choice at the ballot box on December 12."
Mr Woodcock quit Labour with a scathing attack on Jeremy Corbyn's leadership last year.
He had been sitting as an independent since having the Labour whip withdrawn in April 2018 pending investigation of an allegation, which he denies, of sexual harassment.
The former MPs' pleas came just hours after Labour's deputy leader Tom Watson announced he would also not seek re-election.
At a speech in Liverpool, shadow Chancellor John McDonnell claimed Mr Austin was "employed by the Tories", adding: "What else do you expect him to do in an election campaign where you're employed by the Tories, you speak on behalf of the Tories. That's what this was about this morning."
In an interview with ITV News Political Correspondent Romilly Weeks, John McDonnell hit back at Mr Austin's criticism of Labour's alleged lack of action in dealing with anti-semitism.
Mr Austin had cited Labour's alleged inability to root out anti-semitism as a reason for quitting the party in February, and reiterated the criticism again as he urged voters to back the Conservatives on December 12.
Mr McDonnell said: "Ian Austin is quite bitter and he's now been given a job by the Tories so I think his intervention is clearly a political intervention on behalf of the Tory Party.
"The stuff that he's coming out with isn't even worth seriously addressing."
Labour has also come under fire from the Jewish Chronicle on Wednesday, with the newspaper claiming the Labour Party has failed tackle anti-semitism amongst its members.
Mr McDonnell said: "We've introduced new disciplinary procedures, we've kicked people out."
He added: "It's been small and tiny numbers in our party but I say if there's one anti-Semite, it's not good enough, so I think we've got the effective procedures to take us forward."