Labour leader Jeremy Corbyn has been told by deputy leader Tom Watson during crisis talks that he is likely to face a leadership challenge, a senior party source said.
The meeting between Mr Corbyn and the West Bromwich MP was described as "civil" by a spokesman for the leader.
The spokesman said there was "categorically not" any call from Mr Watson for Mr Corbyn to quit.
Toby Perkins, the MP for Chesterfield, has resigned as shadow armed forces minister saying the Labour Party "needs a change at the top".
He said he will stand for leader again if a fresh contest is held amid growing calls for him to stand down within the party.
Labour's deputy leader Tom Watson was enjoying a silent disco at Glastonbury Festival as the party leadership became embroiled in civil war.