David Cameron taunted Gordon Brown today, claiming the Prime Minister had lost control of the Cabinet and that his Government was in “terminal decline”.

The Conservative leader demanded to know why Hazel Blears, the Communities Secretary, had not been dismissed after writing an openly critical article about Mr Brown at the weekend.

Mr Cameron seized on Ms Blears’s “YouTube if you want to” gibe, and other criticisms, asking: “How much more mocking can you get than that? Who on earth do you think she is referring to? Don’t you realise your Government simply cannot go on like this? Why is she still in the Cabinet?”

Mr Brown declined to defend Ms Blears, who was standing to the right of the Speaker during Prime Minister’s Questions rather than sitting in her usual position on the front bench.

Mr Cameron said the Prime Minister was now isolated in the Cabinet, saying “he’s the only one who thinks he’s any good”.

He went on: “No one doubts he might have come into politics for the right reasons, but isn’t it clear he’s just not up to the job?

“The public know it, his party know it and now the Cabinet knows it, so why not do the last bold thing that’s left to him: call an election?”

Mr Brown countered by claiming that the Conservatives were more interested in personalities and politicking rather than the crucial issues facing the country.

But Mr Cameron continued: “A series of U-turns, defeats in Parliament even when the Government has a majority and ministers, including Cabinet ministers, openly questioning the authority of the Prime Minister ... Does the Prime Minister agree that these are signs of a Government in terminal decline?”

Mr Brown, who has suffered a week of setbacks, faces an internal squabble over the future of Royal Mail days after defeat in the Commons over Gurkha settlement rights. He said that with so many economic and political hurdles facing Britain it was shameful that the Conservatives had “nothing to say about the big issues of the day” during the weekly question session.

“I’ve listened to your six questions and not one of them has been about policy," he said. "You’ve never raised the cause of the unemployed, not mentioned mortgage holders and homeowners once. You’ve not mentioned the state of the economy and what we can do to improve it once. You are completely out of your depth when it comes to the big issues.”

He also accused the Tories of making U-turns on education and police spending. “You were the “hug a hoody” – that was another of your big U-turns. Compassionate Conservatism – it’s gone, gone and gone.”

In a sign of the Prime Minister’s wavering authority, MPs roared with laughter as Mr Cameron replied: “I’m sure that sounded just great in the bunker, while the mobile phones were flying and the printers were flying round the room.”

Times Recommends

• Fern Britton: 'I still can't see that I was wrong'
• Extreme cooking
• Easy French: Tarte Tatin