The Washington Post announced Monday that the newspaper’s longtime executive editor, Leonard Downie Jr., is stepping down in September.

Downie, 66, has been the Post’s top editor since 1991 and has led the paper to 25 Pulitzer Prizes, including one for a 2005 story exposing the existence of secret CIA prisons, which President Bush asked him not to publish.

His colleagues have spoken of him as being a straight shooter, fair and very involved in the daily management of the paper.

Donald Graham, the Post’s former publisher, said he chose Downie as his executive editor "because I knew his day-to-day news judgment was superb, that he had a ferocious sense of fairness, that he had great taste in newspeople and because he worked incredibly hard," the Post reported.

Downie started as a summer intern at the paper in 1964, later becoming an award-winning investigative reporter, a Metro desk editor, an assistant managing editor and deputy Metro editor, during which time he supervised the paper’s Watergate coverage.

He worked as the Post’s national editor from 1982 until 1984 and as managing editor from 1984 until 1991.

Rumors of Downie’s departure had been circulating for months after the paper’s new publisher, Katharine Weymouth, met with several newspaper and magazine publishers about the Post’s future after assuming her position in February.

Weymouth is the granddaughter of longtime Post Publisher Katharine Graham, who brought in Ben Bradlee as her executive editor when she took the helm of the paper.

Downie will take the role of Washington Post Company vice president at large when he retires as executive editor Sept. 8.

The Post is facing challenges, including falling advertising revenue, circulation that has declined from a peak of 832,000 in 1993 to 673,000 today and a round of staff cutbacks.

Weymouth said she will announce a new executive editor soon.

Media outlets have named New York Times Deputy Managing Editor Jonathan Landman, Wall Street Journal Managing Editor Marcus Brauchli and Post Managing Editor Phil Bennett as top contenders for the spot.