Unite trade union boss Len McCluskey has issued a warning to Sir Keir Starmer that he will be “dumped into the dustbin of history” if he continues his attacks on the party left.
Mr McCluskey accused the Labour leader of going back on the positions he took when he ran to replace Jeremy Corbyn last year.
He told Times Radio that Sir Keir needed to “shake off the siren voices of New Labour” if the party was to stand any chance of regaining power.
“There is a real fear at the moment that he is attempting to marginalise the left. Now we seem to be travelling in a direction that is turning the Labour Party into a party of the establishment. That will not get you into No 10,” he said.
“Keir needs to start telling people what he is and what Labour are. People don’t know at the moment.
“People knew where Jeremy Corbyn was coming from long before any elections. People knew where Tony Blair was coming from long before any elections.
“At the moment we are suffering because people don’t understand what Keir Starmer stands for or what Labour stands for.
“And that’s what he has to do. Stick to the radical nature of the policies he stood on and win back the red wall seats.
“If he continues to attack the democracy in the left of the party he’ll destroy the unity of the party and the reality will be he’ll be dumped into the dustbin of history.”
From the opposite wing of the party, Lord Mandelson – one of the architects of New Labour in the 1990s – praised Sir Keir, saying that under his leadership the party was now “firmly back in the ring”.
However he said that he needed to begin a review of the party’s policies as he still had Mr Corbyn’s 2019 general election manifesto “around his neck”.
While Lord Mandelson said it would be wrong to make too many specific commitments this early in the Parliament, the party needed polices which were “radical, credible, affordable”.
He said Sir Keir had shown courage by suspending Jeremy Corbyn but warned that his leadership would be “tested and tested again” and he had to be willing to take “a lot more risk”.
“Covid eclipsed everything else. Without it, Keir would have been able to do more in day-to-day politics,” Lord Mandelson told the BBC.
“We have lived through abnormal times, and although he has been tested by it, there is clearly a lot more to do.
“He needs to now pick up speed and work out a real argument and point of difference with the Government.”