Mr Blair wants to remain prime minister, says Mr Byers

Stephen Byers said Mr Blair had a "huge appetite" to remain in the job.

But the former transport secretary told GMTV that, without a Blairite manifesto of real change, voters might think he would not be there to see it through.

Last week Downing Street dismissed reports speculating about how long Mr Blair wants to remain prime minister.

Blair 'indispensable'

Mr Byers said: "I think the acid test will be whether or not we have a clearly Blairite manifesto for Labour in the run-up to the next general election."

Without one, the government risked losing people who voted Labour for the first time when the party took power in 1997, he said.

Culture Secretary Tessa Jowell also backed Mr Blair on the programme, saying his leadership was "indispensable".

Comments by former Labour leader Neil Kinnock last weekend fuelled speculation about Mr Blair's future.

Mr Byers is seen as close to the prime minister

He said it would be understandable if the PM considered "hanging his boots up" after the referendum on the EU constitution.

Some saw this as a signal of a new deal to allow Chancellor Gordon Brown to succeed Mr Blair as prime minister.

But Health Secretary John Reid dismissed reports as "misleading and ill-informed speculation in certain sections of the press".

On Sunday Mr Byers said a third term would give Mr Blair's government the chance to change the political landscape.

He said since 1945, only Clement Attlee and Margaret Thatcher's governments had achieved that.

"I think the third term will be the opportunity to make those big changes and to ensure that we embed a sort of social democratic settlement within the United Kingdom," he said.