The former home secretary David Blunkett has said “anti-Semitism” and “thuggery” in the Labour party now makes him “despair”.
Lord Blunkett, who was an MP for 28 years and now sits as a Labour peer in the upper chamber, said the likelihood of Jeremy Corbyn winning a majority was “extraordinarily slim”.
But he urged moderates within the party to “stay and fight” to ensure the “voice of reason” prevailed, following deputy leader Tom Watson’s decision to stand down.
The former Cabinet minister and party chairman’s comments came after a bruising week for the party which has seen two of its former MPs urge voters to back the Tories instead.
Ian Austin and John Woodcock said they would be supporting the Conservatives as they did not believe Mr Corbyn was fit to be in Number 10.
And on Friday, Dame Margaret Hodge – one of the most prominent Jewish figures in Labour – declined to endorse the Opposition leader as prime minister.
In a letter written to The Telegraph, Lord Blunkett said: “The behaviour of the hard-Left within the Labour Party – the anti-Semitism, the thuggery, the irrational views on security and international issues, and the lack of realisation that you have to embrace a big tent of people in order to win – certainly makes me despair.
“But it also makes the likelihood of an all-out Labour majority in this general election extraordinarily slim. The political landscape right now is completely different to what the hard-Left would have you believe.
The Conservative party under Margaret Thatcher secured a sizeable majority at the 1983 election after votes for the opposition were split between Labour and the Liberal/SDP alliance.
The Labour Party has been contacted for comment.