A crushing by-election defeat by the Tories fuelled reports that Cabinet ministers were prepared to push him from office amid backbench dissent.

But Health Secretary Alan Johnson insisted there was "absolutely no appetite...to change the leader" but conceded the Government needed to look at some shorter-term policies.

And Foreign Secretary David Miliband denied a claim he was preparing a challenge and said Mr Brown remained "the best man for the job".

Ruling himself out of a challenge, Mr Johnson told the BBC these were "really rocky times" but added: "There is absolutely no appetite I believe in the party to change the leader.

Pressure is mounting on the Government to abandon a planned rise in fuel duty this autumn and to axe plans to hit owners of gas-guzzling cars with a massive tax hike.

Mr Miliband said a report that he was preparing to stand for the leadership was "fiction" - pointing out that he had been in the US during the by-election and its immediate fallout.

"There's fiction and there's reality. And the reality is that the Government has taken some beatings but the test is do we have the character and the grit and then the policies and then the vision to go forward and I believe we do. That's what we've all got to get down to."

Newspapers reported that the Prime Minister could be forced to appoint a deputy as a ready-made successor if he was forced out.

Former deputy Prime Minister John Prescott acknowledged that voters had given Labour a "kick in the backside" but said leadership speculation was "nonsense". "We are in a real fight now, we need to take on the Tories and I hope the party and Members of Parliament will get together and address themselves to that fight," he said.