Iain Duncan Smith was fighting for his future last night after a former government whip went public to join those demanding a vote of confidence in his leadership.
Momentum for a vote on Mr Duncan Smith's future is increasing after Derek Conway's announcement that he had sent a letter to the head of the party's backbench 1922 Committee appeared to derail the Tory leader's television appeal to the party.
Mr Conway accused Mr Duncan Smith of a shocking display of arrogance and bluster. He said: "This guy has had his chance. He was never up to the job."
Mr Duncan Smith faced further problems when a main party donor, Sir Michael Bishop, warned that donors would not hand over money until the leadership issue was resolved.
Also, Dominic Cummings, a former director of strategy at Central Office, launched a stinging attack on Mr Duncan Smith's time in charge of Tory headquarters. In an interview with the BBC, he urged the party to "bite the bullet" and get rid of the leader, saying: "Anything would be better than the current situation."
Senior figures believe Mr Duncan Smith has three days to rescue his leadership before the 1922 Committee meets on Wednesday. MPs are nudging nearer to gaining the 25 signatures needed to spark a leadership ballot. Up to 19 letters are thought to have been sent to Sir Michael Spicer, chairman of the committee.
Figures in both loyalist and rebel camps acknowledged that the leader's authority appeared to be ebbing away, with even the whips' office unable to control the situation. Those close to Mr Duncan Smith are said to be resigned to the idea of a confidence vote.
Yesterday, Mr Duncan Smith used his appearance on the BBC's Breakfast with Frost to attack his critics, insisting they were a small group motivated by "personal bitterness and personal ambition". He insisted that he would fight a vote of confidence even if MPs muster the 25 letters needed.
He said: "This party is in the process of being frightened and bullied by a small number of people whose personal ambition and whose personal anger and bitterness is in the process of trying to push the party to the edge of a divisive leadership process which would rip them apart, at the very moment when the public wants us to offer that alternative to Tony Blair."
But Mr Conway joined senior backbenchers in insisting that rebels would have the 25 signatures needed to trigger a vote within days and even loyal shadow cabinet members admitted the leader had only a "50-50" chance of survival.
Mr Conway said: "It was absolute arrogance to claim, as he did, that he was our only hope. There are at least half a dozen members of the Shadow Cabinet who would be much more competent to do the job and I think if we remove Mr Duncan Smith the Tory party's fortunes will be transformed by this time next year. There is a crying need for the party to get behind a competent leader. Any one of those alternatives being considered are capable of fighting and kicking the hell out of Labour."
John Greenway, a former Tory frontbencher, urged Mr Duncan Smith to initiate a confidence vote to end speculation. He said: "I think it is for him now to demonstrate he has the courage to call for that vote of confidence, and if he does, then I think support for him will grow."
Sir Michael, executive chairman of British Midland airline, warned there was "no money of any substance" coming into the Conservative Party to fund either the election or the running of the party. He added there would be a brake on new funds until the leadership issue was resolved.
He said: "The Conservative Party has been really staring into the abyss not just in the past few weeks but for six years since the 1997 general election."
Mr Duncan Smith's allies made efforts to orchestrate a show of support from MPs and donors. They lobbied local party activists to pressure dissident MPs in an attempt to defuse the rebellion.
They were offered hope in a BBC Radio survey of local party chairmen, suggesting that more than three quarters of chairmen believe Mr Duncan Smith should not face a vote of confidence.
Of the 126 chairmen who responded, 87 said they did not want a confidence vote in Mr Duncan Smith and 62 thought that changing the leader would make the party's electoral prospects worse.
Rumours were rife about deals among potential candidates to ensure any move to topple Mr Duncan Smith would not result in a bruising and divisive battle for the succession. But most shadow frontbenchers have ruled out the idea of a so-called coronation of either Michael Howard or Kenneth Clarke .