Tom Watson urges unity behind Corbyn amid Labour split rumours
Labour's deputy leader Tom Watson has urged his party's MPs to stay united amid speculation some might leave over dissatisfaction with Jeremy Corbyn.
Asked if a breakaway was "unstoppable", Mr Watson said: "I hope it isn't."
Some MPs are frustrated at Mr Corbyn's refusal to back a further Brexit referendum, despite a vote at the party conference to keep the option open.
Former shadow chancellor Chris Leslie told MPs backbenchers were "being played for fools" by the leadership.
"The idea that the Labour party is not together and arguing against this disaster is, for me, entirely heartbreaking," he said, during the latest Brexit debate in the Commons.
He pointed out an amendment tabled by Mr Corbyn, which attempts to ensure MPs are given a vote on Theresa May's deal by 27 February, makes no specific mention of a further referendum with the option of remaining in the EU.
"Why are we regressing on our policy passed at the September conference?," he asked.
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Earlier, Treasury spokesman Clive Lewis had told pro-EU activists the ramifications "will be severe" if Labour is seen to facilitate a "Tory Brexit".
"We are now sending some mixed messages out there and that is dangerous," he said.
And backbencher Angela Smith told BBC Look North backbench MPs were uncomfortable with the leader's stances on a number of issues.
"We are being pushed to the edge on Brexit, on Venezuela, on anti-Semitism, and it's for Jeremy Corbyn... to show the Labour party is a broad church," she said.
But Mr Watson told BBC Radio 4's World At One: "I want this party to stay together. People should stay and fight their corner. We need an electorally viable Labour Party."
He said people should "do everything they can" to stop a breakaway.
"For the last two years, I've been trying to hold everyone together. I think we need all voices round the top table of the Labour Party. We need all factions represented. People expect the Labour Party to be united."
Another who attended the Another Europe is Possible event, Rachael Maskell, played down the threat of a breakaway.
She said Labour MPs had a responsibility to focus on getting into government.
"Noises off do not help our party to achieve that," she added.
By BBC Political Correspondent Iain Watson
Some people close to the Labour leadership believe a breakaway is all but inevitable - but that it will be small.
This is partly because the anti-Corbyn forces aren't entirely united.
None of the people at the pro-referendum event addressed by Clive Lewis will break away even though some are very unhappy with the party's Brexit stance.
They are on the left.
And other pro-Europeans from the Blair/Brown era who are minded to go aren't united on timing.
For them, there has to be a series of triggers first:
- Jeremy Corbyn has to be seen, as it were, to be the midwife of Brexit
- He has to be perceived as not tackling anti-Semitism robustly enough
If not all the triggers are pulled, some MPs in this group will stay put.
Then we have a cluster of politicians who really really dislike Jeremy Corbyn - and quite a few are potentially facing de-selection by their local parties.
But some are Eurosceptic and would have difficulty joining a pro-EU breakaway.
So it may be more likely that people initially resign the whip rather than conjure up a whole new party.