Keir Starmer's attempts to win support for his divisive welfare Bill are failing completely, as the number of Labour MP rebels actually grew yesterday. The Prime Minister, Chancellor and Welfare Secretary are trying to force through modest cuts of £5 billion a year from the country's unaffordable welfare bill, but he's now facing his biggest Commons rebellion yet.

His parliamentary whips, who attempt to bully or persuade MPs into voting the way the Government wants, spent much of yesterday claiming that a vote against the cuts could event spark a general election. On Tuesday morning, 108 MPs had signed a wrecking amendment that would cause the Bill to fail. However despite Labour whips' best efforts, by the evening that number had risen to 125. One Labour MP claimed that ministers and whips had resorted to claiming the Bill will be treated as a confidence vote in the Government, meaning that if it fails it would spark a general election.

The MP hit back: "I would be happy to see a leadership contest, I think perhaps it's time for change."

Meanwhile Rachel Reeves spent the day claiming that voting down the cuts would "devastate" the government finances and damage Sir Keir's authority so badly it could bring him down.

One minister told the Times that the mood in government is now one of "panic", and could be about to delay next Tuesday's Commons showdown to buy time.

A Labour insider told the Mail: "The whole thing is a massive f*** you to Keir and Rachel."

The Prime Minister insisted yesterday that the cuts are "not a confidence vote".

However Ms Reeves would be left with a huge financial blackhole which she would have to fill at the autumn Budget with cuts elsewhere or break her manifesto pledges on tax rises.

Speaking at the G7 last week, Sir Keir was bullish on rejecting any further concessions to his hard-left backbench rebels.

He told reporters flying to Canada: "We've got to reform the welfare system. Everybody agrees with that proposition. So we've got to do that basic reform. It doesn't work for those that need support and help into work and it doesn't work for the taxpayer. So it's got to be reformed."

"The principles remain the same, those who can work should work. Those who need support in to work should have that support in to work which I don't think they are getting at the moment.

"Those who are never going to be able to work should be properly supported and protected. And that includes not being reassessed and reassessed. So they are the principles, we need to do reform and we will be getting on with that reform when the Bill comes."

The row has already seen one Labour frontbencher quit in order to support the wrecking amendment, but it's feared more could go if the PM presses on.

Sir Lindsay Hoyle, the Commons Speaker, is also being pressured to reject the amendment altogether and save the Government's bacon.

Yesterday Tory leader Kemi Badenoch offered the PM a lifeline, saying she would whip her MPs to support the cuts provided he goes further and promises no more tax rises later this year.