Two Labour MPs have submitted a motion of no confidence in their leader Jeremy Corbyn for failing to give party voters a clear message on the EU referendum.
Dame Margaret Hodge and Ann Coffey confirmed the move in a letter to the Parliamentary Labour Party chairman.
The motion has no formal constitutional force but calls for a discussion at their next PLP meeting on Monday.
The chairman will decide whether it is debated. If accepted, a secret ballot of Labour MPs could be held on Tuesday.
By early Friday evening, seven other Labour MPs were on record as backing the motion.
Asked if he will resign, Mr Corbyn, who campaigned on the losing Remain side, said: "No, I'm carrying on.
"I'm making the case for unity, I'm making the case of what Labour can offer to Britain, of decent housing for people, of good secure jobs for people, of trade with Europe and of course with other parts of the world.
"Because if we don't get the trade issue right, we've got a real problem in this country," he told Channel 4 News.
"It may be brutal, it may be bloody, but he has to go. We have no choice."
That's the view of a former Labour minister who's plotting to oust Jeremy Corbyn.
But there was no immediate support from the current frontbench.
Labour's shadow cabinet met for nearly three hours this morning and there were no explicit calls for the leader's resignation.
But there was sustained criticism of the way Jeremy Corbyn had conducted the referendum campaign and what was seen as his failure to address concerns about immigration, and one source insisted: "He was not enjoying the confidence of the room."
result.
Labour MPs submit Corbyn no confidence motion - BBC News