Tony Blair seriously considered stepping down as prime minister earlier this year because of "personal and family" pressures, an old friend suggested yesterday.

The Labour peer, Melvyn Bragg, whose wife, Cate Haste, co-authored Cherie Blair's new book on Downing Street spouses, made the claim during an interview with ITV News.

Asked by Alastair Stewart if the prime minister "nearly did go and call it a day", Lord Bragg replied: "I think that he [Blair] was under tremendous stress. He was being hammered in the press. Perhaps he had doubts about some policies, perhaps not.

"But in my view, the real stress was personal and family, which matters most to him. And my guess is that the considerations of his family became very pressing and that was what made him think things over very carefully. That is my guess," he said.

He later added that he was not suggesting matrimonial problems - "I have never seen a couple get on as good as those two".

Last night Blair's official spokesman said: "I must admit it took us by surprise as much as anybody else. I don't know why he said it. What Lord Bragg said is a matter for Lord Bragg and not for us."