Butler and by-elections will make it a tough week for Blair

Tony Blair is working with senior aides this weekend on a survival strategy to overcome a battering from the Butler report and a backlash against the war on Iraq in two Labour by-elections.

The Prime Minister, who is spending today and tomorrow at Chequers, has been told by his senior officials that next Thursday's report by the committee under Lord Butler of Brockwell, a former cabinet secretary, will be bad for the Government but it will not contain a "silver bullet'' that would lead to resignations.

Mr Blair has rejected the advice of allies who urged him to blame John Scarlett, the former head of the Joint Intelligence Committee (JIC). He was promoted to take over as head of MI6 from 1 August, despite facing criticism in the report.

"Some of the intelligence was wrong. But we will not dump on the intelligence services," a Blair aide said. "We hope it will be a one-and-a-half-day wonder and that life will go on."

The Butler report is expected to criticise the Government's communications operation for the way it presented intelligence to the media, allowing the false impression to be given that Iraqi weapons of mass destruction could be used in 45 minutes against British assets in Cyprus. It will also question the judgement of Mr Scarlett in allowing JIC intelligence to be published in the infamous dossiers on Iraq's weapons.

On Monday Gordon Brown will announce a substantial rise in spending on the intelligence services and other services in his comprehensive spending review. There are concerns in Downing Street that Mr Brown will have a "good week", leaving Mr Blair more vulnerable, particularly after the expected by-election defeats in Leicester South and Birmingham Hodge Hill.

Whitehall departments havebeen told by Downing Street that it wants to provide good news as part of the fight-back strategy, including an announcement on tackling the shortage of NHS dentists that has been taken over by No 10 and pencilled in for Friday.

Clare Short, the former overseas development minister, last night accused Downing Street of preparing for the Butler report with more media gloss. "There is lots of spin going on. I don't think it is coming from Butler," she said. "It looks like it is coming from No 10 to exaggerate it so that it doesn't seem so bad when the report is published."

The report will confirm that Jack Straw, the Foreign Secretary, overruled legal advice against the war by the Foreign Office legal adviser, Elizabeth Wilmshurst, who resigned.The Attorney General, Lord Goldsmith, will also be criticised.

Ms Short said: "The word also went out that the attorney didn't think there was legal authority and the military wouldn't go to fight a war without it. Then there was a long silence. ... The rumour was that he went shopping and found the only international lawyer who thought there was authority."