Even Blair loyalists find it hard to see how he can survive

Tony Blair has been dubbed "the Houdini of British politics" because, when his demise is predicted, he always manages to wriggle free. He survived the Iraq war, a rebellion over university fees and the Hutton inquiry. But, as the vultures circle again, a growing number of Labour MPs believe that the crisis engulfing the Prime Minister over Iraq may be his downfall.

"There is no escape," one Blair loyalist said yesterday. "I don't want him to go but I honestly can't see a way out this time. I wish I could."

The chatter about Mr Blair's future at Westminster this week is much louder than it was two weeks ago, when ministers rallied round after the botched announcement of a referendum on Europe.

The pictures showing the mistreatment of Iraqi prisoners have had a devastating effect on the morale of Mr Blair's backbench troops. The irony is that, although most of the blame lies with American forces rather than their British partners, the British Prime Minister is suffering the bulk of the political damage.

The harrowing photographs have called into question his shoulder-to-shoulder support for the Bush administration, and his justification that it would buy him influence. They have blown apart his most recent justification for war, the "moral" case for toppling Saddam Hussein because of his record on human rights, on which he has increasingly relied after the failure to find weapons of mass destruction.

To make matters worse, the Government's handling of reports containing evidence of mistreatment has been incompetent. "Why Geoff Hoon did not ask to see the Red Cross report beggars belief," said one Blairite MP.

The controversy has also eclipsed the latest in a long line of attempts by Mr Blair to switch the spotlight back to domestic issues. Labour MPs predict worse than expected results for the party at the European and local elections on 10 June. That is dangerous for Mr Blair. If poor results are blamed on Iraq, he will be held responsible. His trump card in his own party - "we may not like him, but he's a winner" - may disappear.

Anxious backbenchers will work out their prospects of survival after 10 June. If they fear the worst, the current gossip could turn to panic and plotting against Mr Blair.

A coup would almost certainly require cabinet-level support. There is no sign yet that ministers are turning against Mr Blair. But some might wobble if they came under pressure from backbenchers after the elections. A former minister said: "Cabinet ministers have got to go to him if we do badly and tell him to make way for Gordon [Brown]." The Chancellor is dissociating himself from any plotting. But his backbench supporters are eagerly watching developments.

John Prescott gave a public show of support by sitting next to Mr Blair at Prime Minister's Questions yesterday. Ministers patrolled the Commons bars and tearooms in strength this week as they tried to quell the rumblings against Mr Blair. "It shows you how rattled they are when they appear in the Strangers Bar," said a Labour MP. Ministers reported back an unpalatable message to No 10.

"Everyone knows that we cannot go on like this," one minister said last night. There are two possible escape routes for Mr Blair in the eyes of his advisers. Route one would be to distance himself publicly from President George Bush, perhaps in a keynote speech on the future of Iraq, perhaps by joining forces with France and Germany to produce a Europe-led solution to the crisis in which the United Nations would be given the pivotal role.

It might provide some respite for a beleaguered Mr Blair. But it is unlikely to happen. To Mr Blair, it does not feel like it is "the right thing." It might also run the risk of being a U-turn too far, an admission that his "up close and personal" strategy with a right-wing US President was a mistake all along.

Route two is more plausible: Mr Blair must prove he has real influence by persuading the US to change its strategy in Iraq and produce an "international solution" through the UN. "We have got to end the tunnel vision in Washington," said one Blair aide. This option appeals to the Prime Minister, who insists all he wants is the right result for the Iraqi people.

Mr Blair showed no sign of distancing himself from President Bush during Prime Minister's Questions but his performance played badly among some Labour MPs. "How dare he suggest that it is unpatriotic to protest against the treatment of prisoners?" said one anti-war MP.

One left-winger said: "He will have to go after 10 June. That is why we are going relatively quiet. The last thing he will do is go if we call for him to step down."