Insiders have revealed how proposals for new pro-European centre party called Start Again have been openly discussed during cross-party meetings on Brexit said Mr Corbyn’s attitude after the attempted murder of a Russian spy on British soil had brought the split a step closer.
A former shadow cabinet member said Mr Corbyn’s refusal to join world leaders such as Donald Trump, Angela Merkel and Emmanuel Macron in blaming Russia for the outrage would lead to some MPs leaving Labour.
The MP is quoted as saying: “This is a watershed moment. It has caused a number of people to question why we are in this party.”
Pro-remain MPs and peers, including former shadow business secretary Chuka Umunna, former shadow chancellor Chris Leslie, Wirral South MP Alison McGovern and Tory remainer Anna Soubry meet every Wednesday.
A source present at several of the meetings told the Sunday Times Mr Umunna had suggested the combined pro-EU activists in Britain are a force to be reckoned with if brought under the same roof.
The source said: “I have heard him on three occasions, in groups of 10 people or more, mention the fact that if you put together the memberships of the pro-European movements you would have something bigger than the Labour Party.
“Start Again is the working title.”
Mr Umunna denied seeking to start a new party, describing the reports as “nonsense”.
But splits have now started to develop in Mr Corbyn’s inner-circle over his lacklustre reaction to the attempted assassination of former Russian double-agent Sergei Skripal and his daughter Yulia in Salisbury on March 4.
Some officials are beginning to doubt the wisdom of Mr Corbyn’s chief aide Seumas Milne questioning intelligence suggesting Russia was behind the outrage.
The Labour leader has been briefed by national security adviser Sir Mark Sedwill but was not shown top secret intelligence and pointedly was not invited to join the national security council.
A party aide said: “The vast majority of people — basically everyone but Seumas — think that what he is saying on Russia is bonkers.
“When you are in touching distance of power, many in the leader’s office think it’s really unwise.”
Mr Corbyn’s stance has prompted moderate Labour MPs to discuss whether they should sit as a separate faction in parliament if Labour were to win most seats at the next election.
One said: “The question we are asking is: how can you, as a patriot, countenance him being prime minister?”