Acting Labour party leader Harriet Harman Labour was on Monday night in disarray after a fifth of the party’s MPs rebelled during a vote on Tory welfare reforms.
Miss Harman believes that her party should not oppose all of George Osborne’s benefits cuts in a bid to avoid the charge that Labour is the “party of welfare”.
Rather than voting against the bill, Miss Harman wanted her backbenchers to vote for a Labour amendment and to then abstain on the second reading of the welfare.
But scores of furious Labour MPs decided to vote against the bill, with a number accusing Miss Harman of being “a Tory in disguise”. The rebellion underlines the split in the Labour Party in the wake of the general election.
Jeremy Corbyn was the only candidate for the leadership of the party to rebel against Miss Harman.
Work and Pensions Secretary Iain Duncan Smith said: “Nearly 50 Labour MPs have defied their leadership and opposed our welfare reforms which will move our country from a low wage, high tax and high welfare economy to a higher wage, lower tax and lower welfare society.
“It’s clear that Labour are still the same old anti-worker party – just offering more welfare, more borrowing and more taxes.”
In a post on Facebook after the vote, Andy Burnham claimed he would now oppose the bill despite refusing to vote against it in the Commons.
“Tonight I am firing the starting gun on Labour’s opposition to this bill,” he said. “If I am elected leader in September, I am determined that Labour will fight this regressive bill word by word, line by line.”
It came as Mr Burnham, the frontrunner for the leadership, has been accused by MPs of damaging the party by “flip-flopping” over whether to oppose the controversial welfare reforms.
In a series of hustings during the leadership contest, Mr Burnham had expressed anger at Ms Harman’s decision not to oppose the welfare measures after she suggested there was no public appetite for rejecting them.
But the shadow health secretary issued a statement in a letter to fellow MPs hours before the vote saying he would now abide by collective responsibility by abstaining.
One MP described his behaviour as “inexcusable”. He told The Daily Telegraph: “There was never any question that Andy wasn’t going to fall into line. It would have looked terrible for him had he rebelled – for a start he would have had to resign from the shadow cabinet. His posturing on this has made a lot of people on his own side furious.”
A spokesman for Mr Burnham rejected the suggestion he had “wobbled”, saying his leadership over the cuts had persuaded Miss Harman to table a “reasonable amendment” to the Bill.
In his letter to MPs, Mr Burnham said: “Collective responsibility is important and it is what I would expect as leader of our party. “It is why I will be voting for our reasoned amendment and, if it is defeated, abstaining on the Bill.