London ? lastair Campbell, the combative, acid-tongued aide who shaped Prime Minister Tony Blair’s image and became a key figure in the crisis surrounding the government’s Iraq policy, announced his resignation Friday.

The Downing Street communications chief, who has been at the center of a furious dispute over whether Blair’s office manipulated intelligence about Iraqi weapons in the run-up to war, said he was stepping down within the next few weeks for personal reasons.

The decision leaves Blair to face the biggest crisis of his career — the corrosive dispute about Iraq and the suicide of a government scientist caught up in the storm — without one of his most trusted advisers. It also is likely to be seen as an admission that someone in government must accept blame for the dispute.

Blair praised Campbell as “an immensely able, fearless, loyal servant of the cause he believes in who was dedicated not only to that cause but to his country.”

But in a nod to critics of Campbell’s power, which went far beyond that of a press spokesman, Blair’s office said his successor, former Labor Party communications director David Hill, would oversee a restructured communications office.

Campbell, a former political journalist who began working for Blair in 1994, was widely considered the most powerful person in the government after his boss, and often was called “the real deputy prime minister.”