A tetchy Jeremy Corbyn today refused to say he will quit if he loses a looming general election - despite allies publicly admitting he would have to fall on his sword.
Amid mounting evidence that he is losing his grip on the Labour Party, the veteran left-winger insisted he would not engage in 'hypotheticals'.
The 70-year-old also delivered a thinly veiled dig at long-time ally John McDonnell, who said last week that the leader will have to stand aside if the election is lost.
But shadow business secretary Rebecca Long-Bailey immediately risked inflaming the row by saying Mr Corbyn would have to abide by 'convention' and go.
Speculation has been growing about Mr Corbyn's future after last week's alleged 'demotion' of key aide Karie Murphy.
The shock decision to move chief of staff Ms Murphy from the leader's office to the party's London HQ was viewed in some quarters as a sign he is losing control.
Jeremy Corbyn (pictured on Sky News' Ridge on Sunday today) delivered a thinly veiled dig at long-time ally John McDonnell, who said last week that the leader will have to stand aside if the election is lost
Mr McDonnell and other senior figures are pushing for Labour to move four-square behind a second Brexit referendum - a shift which is thought to have been resisted by Ms Murphy.
Speaking on Sky News' Ridge on Sunday today, Mr Corbyn said: 'We are not expecting to lose the next election. It is a hypothetical question. It is up to the members of our party to decide who the leader is.
'John gave an answer to an interview that he undertook. My answer is this: I am leading this party to go into an election.'
However, Ms Long-Bailey, regarded as Mr McDonnell's choice for the next leader, took a rather different stance when she appeared on the BBC's Andrew Marr Show.
'I think that it would fantastic for the next Labour leader to be a woman…it's a hypothetical situation at the moment,' she said.
'We're fighting for a general election to elect Jeremy Corbyn as our Prime Minister and we think we're in touching distance of that, but I think it's right for John to say that in the event of us losing an election that they would stand aside.
'That is convention within the party that's usually what happens.'
In his interview with GQ last week, Mr McDonnell said he did not believe Mr Corbyn could stay on after another election defeat,
'I think it is the same for my own personal position, I can't see so,' he said. 'What we'd do is as the tradition, which is have an election for a new leader.
'I'm still of the view now that whoever comes after Jeremy has got to be a woman. We've got to have a woman leader. If you look at the new youngsters that have come through, they are fantastic.'
John McDonnell, pictured in Colchester earlier this month, has suggested he would be open to backing a second referendum before a general election