The prime minister has welcomed the prospect of Michael Howard becoming the next Conservative leader.

In a radio interview on Thursday Tony Blair said his "old adversary" would help define the differences between the government and opposition.

"As you get closer to an election date, then it will become much more an argument about policy and when people look at the [Conservative's] policies, where they stack up they are extreme and where they are not extreme they don't stack up," he told BBC Radio 2.

"I think that will become very, very obvious when you get into a policy debate.

"And so when people say to me, 'well there is a new Tory leader there's going to be a difference', yes there will be a difference but it will be a difference I think in the sense that it will become a much more real, acute political debate and personally I think that is a good thing."

Blair, who shadowed Howard as employment secretary and on home affairs, said the favourite to succeed Iain Duncan Smith was a "good performer".

"It will make the choice far more real for people and also far more stark and I think it is a good thing if the country has a very, very clear policy divide," he said.

"The last few weeks has all been about Mr Duncan Smith - does he stay, does he go and all the rest of it - I think for all of us who have been by-standers in that it will be good to get back to a proper political debate where you say here are the problems of the country and here are some solutions."

Liberal Democrat parliamentary chairman Matthew Taylor MP said a Howard leadership would remind voters of his role in the Major government.

"The decline of the Conservative Party is due to out of touch policies cutting public services, economic incompetence and splits which imposing Michael Howard on party members will do nothing to change," he said.

"Michael Howard will remind voters why 18 years of Tory government was so devastating for Britain.

"The raft of uncosted, unfair and socially divisive policies that the Tories launched at their conference would condemn any leader who tried to sell them to the people of Britain."