Sir Keir Starmer's authority as Labour leader was waning on Thursday night as he signalled that he could row back on plans to change the rules of the party's leadership elections.
Just 24 hours after announcing proposals to abolish the one member, one vote system used to elect Labour leaders, Sir Keir admitted he may water down or delay them amid opposition from trade unions and his own top team.
Left-wing MPs have suggested that he should make the rule changes a confidence issue and trigger a leadership election if he wishes to continue with them.
Several of the most powerful trade unions, including Unite, Labour's biggest funder, are opposed to the idea of returning to an electoral college – the system used before Ed Miliband's tenure as leader.
Sir Keir's team had hoped reform of the system could be pushed through at this year's party conference, which begins on Saturday. It is thought an electoral college would favour moderate candidates and prevent the rise of another hard-Left leader such as Jeremy Corbyn.
The electoral college system gives members, unions and Labour MPs each a third of the votes in a leadership election. Under the current system, every individual in the Labour movement gets one vote.
A number of MPs and shadow ministers in Sir Keir's team oppose the move to abolish one member, one vote, believing it represents an undemocratic power grab.
John McDonnell, the former shadow chancellor, said the Labour leader had attempted a "grubby stitch-up" and suggested Corbynites could push to topple him.
"If he wants to plough ahead, in all honesty he should go back to the people who elected him in the first place and say: 'Look, this is what I didn't tell you. This is what I want to do,'" he said. "And yes, that does mean a leadership election. Why not, if he feels so strongly about this?"
Sam Tarry, a shadow minister and close ally of Angela Rayner, Sir Keir's deputy, said: "I cannot support a regressive plan to dilute Labour members' votes and divide our movement."
Sir Keir had hoped he would secure the backing of moderate unions such as Unison, the GMB and Usdaw, for his plans. But in a meeting of the Trade Union and Labour Party Liaison Organisation on Wednesday, no unions gave their backing to the plans, while the GMB failed to attend.
Tensions could erupt again
Meanwhile, Unite, Labour's biggest union backer, called for the proposals to be delayed until after the conference, with insiders claiming their calls had been echoed by the other unions present.
Sir Keir sought to play down the suggestion he was at odds with the unions, describing his conversation with general secretaries as "positive".
"I look forward to continuing those conversations through the coming days because the principles are important and we have to look at how we need to change to win again," he said.
It appears increasingly likely that the plans will not be brought forward at conference. A final decision on whether the motion will be put to Labour members and the unions will be taken no earlier than Friday.
Allies of Sir Keir insisted he had not backed down in the meeting, adding that discussions about taking the plans forward into conference would continue overnight and into Thursday. One added that figures close to the Labour leader remained determined to settle the matter at conference, suggesting tensions could erupt again before the weekend.
Meanwhile, Sir Keir was also facing a backlash from moderate MPs on his own wing of the party, who claimed they had been blindsided by the proposed rule changes.
One told The Telegraph: "Everyone was caught on the hop by it. A load of people had argued under Ed Miliband that this [moving to one member, one vote] was the right thing to do, and now they're being asked to support going back to the electoral college."