Speculation is mounting that several Labour MPs could be about to quit the party.
Key figures believed to be on the verge of leaving did not respond to requests for comment.
Former shadow cabinet minister Owen Smith said he was “not commenting” on the rumours, linked to anger over how the party is dealing with Brexit and allegations of anti-Semitism.
Labour MP Stephen Kinnock told BBC Radio 4’s The Westminster Hour on Sunday: “The talk has been going on so long that I say with great regret that yes, there probably will be some kind of splintering.
“It just seems to have been in the rumour mill so long that it’s unlikely that wouldn’t be the outcome.”
On Sunday morning, shadow chancellor John McDonnell said he did not see “any need for anybody to split from the party”.
Mr McDonnell also revealed Labour would “look at” a proposal put forward by backbenchers Peter Kyle and Phil Wilson to back a second Brexit referendum in the next round of Brexit votes on February 27.
Former Labour vice chairman Michael Dugher said at the weekend that he is intending to leave the party, saying he regards it as “institutionally anti-Semitic”.
Mr Dugher, who was elected as MP for Barnsley East in 2010 and left Parliament in May 2017, claimed the party he joined nearly three decades ago “no longer exists”.
He served as vice chairman of the party under Ed Miliband between 2011 and 2014 and later became shadow secretary for transport and culture.
Labour disclosed last week it had received 673 allegations of anti-Semitism by its members over the past 10 months, leading to 12 individuals being expelled.
Writing in the Sun on Sunday, Mr Dugher said the Labour Party had repeatedly failed to “adequately tackle anti-Semitism”.
The now chief executive of UK Music said: “I will continue to have lots of dear friends in the Labour Party, including many talented MPs and hard-working local councillors who are fantastically dedicated public servants.
“Yet in all good conscience, I can no longer justify paying subs to a party which I now regard as institutionally anti-Semitic.”