Former Labour leader Lord Kinnock has urged Jeremy Corbyn to give up his battle to remain as leader of the party in the face of overwhelming opposition from Labour MPs.
Kinnock, who lost to John Major in the 1992 general election, also said Corbyn would have to secure the backing of at least 50 MPs and MEPs in order for his name to be on the ballot if any contest reached the final stage of the vote of Labour members.
"Obviously, there's no basis on which Jeremy could or should stay," Kinnock told Andrew Marr this morning.
He also called on union bosses who were big backers of Corbyn in last year's leadership election, to say to him: "For the sake of the party, and its potential, for the sake of democratic socialism, you have to step down."
However, Len McCluskey, the general secretary of Unite, attacked Kinnock and other party grandees for trying to unsettle the Labour leader, branding it a Blairite coup.
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For his part, Tony Blair refused to specifically call on Corbyn to step down this morning. On Sky's Murnaghan programme he said: "I don't know what's happening in the Labour party right now." He did hint, however, that he would back the removal of Corbyn, saying, "most people can probably guess my views on this."
Kinnock added that he suspected Corbyn's wide appeal in the Labour party membership may be dwindling. "It remains to be seen how many members of the Labour party would support him in a vote," he told the BBC's Andrew Marr.
The former leader, who many see as kick-starting the process of reform which culminated in Tony Blair's landslide 1997 election victory, himself had to see off a leadership contest from Tony Benn in 1988. In that instance, Kinnock needed to secure nominations from MPs to get his name on the ticket for the ballot of party members. He said the same rules would still apply, meaning Corbyn would need the formal support of 50 MPs and MEPs.
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Last week the leader lost a vote of confidence in him among the parliamentary party, with only 40 MPs backing him to stay on against 172 that called for him to step down. Kinnock said Labour party rules state that any leader that does not command the "substantial backing" of the party's MPs should step aside.
However, the Labour leader this morning said he would stand in any contest and was "ready to reach out to Labour MPs who didn't accept my election and oppose my leadership - and work with the whole party to provide the alternative the country needs."