Campbell, whose long-awaited diaries are published Monday, told the newspaper that Blair wanted to announce his decision in mid-2002, nine months before the US-led invasion of Iraq in March 2003.

But Campbell said he warned Blair that he would become a "lame duck" prime minister, even if he reasoned it would allow him to make unpopular decisions without worrying that he would be voted out at the ballot box.

"We had been going through a lot of crap," he explained, adding the idea was abandoned because of the pressure of events and the impending military action in the Gulf.

Blair eventually announced in September 2004 that he would not contest a fourth general election as leader of the governing Labour Party but said he would serve a full third term of office.

Many political commentators have said that this "pre-announcement" to resign did make him a "lame duck" after the 2005 general election as the media focused increasingly on when he would step down, as he did not specify a date.