Blair tells Labour to continue his reforms or face election defeat

Tony Blair is to warn the Labour Party that it will risk losing the next general election if it turns its back on his reform drive after he leaves Downing Street.

In a keynote speech on Saturday, the Prime Minister will stress his determination to influence the policy agenda to be pursued by his successor - almost certainly the Chancellor, Gordon Brown. He will argue that "renewal", which has become a Brownite word for a change of leadership, must involve a new wave of reforms.

Addressing Labour's National Policy Forum, Mr Blair will say New Labour needs to be renewed, not abandoned. One close ally said: "He is leaving, but New Labour must not leave with him. He wants more New Labour, not less."

Mr Blair's comments will be seen as an attempt to manage his departure from No 10 on his own terms. He will call for a more open, candid debate on policy to make clear to to the public the dividing lines between Labour and a revived Conservative Party. However, Mr Blair's ability to influence the policies that will follow his departure is a sensitive issue. Brownite MPs say Mr Blair will have to "let go" and allow Mr Brown a free hand. They insist the Chancellor will map out Labour's long-term agenda in wide-ranging spending review to be published next summer.

The Brown camp resents the suggestion from ultra-Blairites that the Chancellor is anti-reform or opposed to New Labour, pointing to his backing for the Prime Minister on pensions, nuclear power and renewing Britain's Trident nuclear missile system.

In an attempt to rebut the charge by the former home secretary Charles Clarke that he has lost direction, Mr Blair plans a policy blitz before Parliament begins its summer recess next month on crime, energy supplies, the Child Support Agency and health.

Allies of Mr Blair dismissed newspaper reports yesterday that he might announce plans to stand down next spring when he addresses Labour's annual conference in Manchester in September. Advisers have warned him that he would be a "dead duck" if he were to leave such a long lead time between an announcement and his departure date. The Blair and Brown camps said there had been no talks between the two men on how to manage a potentially difficult party conference.

In Saturday's speech, Mr Blair will also turn his fire on the Tories, pointing up what he regards as the inconsistencies in David Cameron's approach - for example, his plan to replace the Human Rights Act with a Bill of Rights.

Mr Blair taunted the Tory leader in the Commons yesterday and challenged him to debate his policy. "I'm surprised when you've just announced a major change to the British constitution that you don't want to get up and debate it," Mr Blair told Mr Cameron at Prime Minister's Questions.

In turn, Mr Cameron challenged Mr Blair on whether MPs would have a vote on whether to approve the renewal of Trident - saying that Mr Brown was in charge after announcing his support for the move last week.

The Tory leader told Mr Blair: "Isn't there a danger that you are just becoming the David Brent of Downing Street - utterly redundant, you are just hanging round the office."