Lord Robert Winston has suggested Jeremy Corbyn should offer to resign in order to prove that he is not antisemitic.
The scientist is one of 67 Labour peers, including Peter Hain and Peter Mandelson, who signed a full-page newspaper advertisement accusing the Labour Party of welcoming everyone “except, it seems, Jews”.
Lord Winston told talkRADIO’s Alastair Stewart that the Labour leader has failed to show leadership by rooting out alleged antisemitism within his party.
“He has to prove that he’s not antisemitic, or he has to accept he’s being manipulated by a very dark part of the party at the present time which is almost Stalinist,” he said.
“What this advertisement is really about is about leadership and what he has not done is to take decisive actions, which he could have taken immediately and dealt with and he hasn’t done that.”
He added: “He has consistently fobbed it off with simple excuses which in fact after two years no longer hold any value to us.”
Over 60 Labour peers signed the advert in the Guardian newspaper
The Jewish peer said Mr Corbyn should consider stepping down after nearly four years in the job.
“I think he could stand down and offer to resign and then perhaps have some honour. But he’s losing that at the moment, that’s one thing he could do,” he said.
“The trouble is you can be an antisemite without realising it.”
In response to the ad, a Labour Party spokesman said Mr Corbyn and the Party “are fully committed to the support, defence and celebration of the Jewish community”.
“Jeremy Corbyn has made clear in interviews, videos and articles that there is no place for antisemitism in the party,” the spokesman added.
The Labour leader is expected to meet with his shadow cabinet and MPs on Monday to discuss the issue.