Snow learnt in March last year that the cancer had returned and underwent chemotherapy.

He said his decision to resign as press secretary was for financial, not health, reasons. He had earned far more as a commentator than his White House salary.

'Conservative commentator'

As press secretary, Snow brought a partisan angle to the task of explaining and defending the president's policies. During daily briefings, he challenged reporters, scolded them and questioned their motives.

Critics suggested that Snow was turning the traditionally informational daily briefing into a personality-driven media event short on facts and long on confrontation.

He was the first press secretary, by his own account, to travel the country raising money for Republican candidates.

Most of Snow's career in media involved expressing his conservative views and support for the US Republican party.

But as a commentator, he had not always been on the president's side. He once called Bush "something of an embarrassment". He also criticised what he called Bush's "lacklustre" domestic policy.