Tom Davis was just 30 when he ran his first race in 1979 for a seat on the Fairfax County Board of Supervisors that Democrats had held for almost a decade.

The lawyer, who had grown up in Arlington County, was a bred-in-the-bone Republican. His grandfather was undersecretary of the Department of the Interior under President Dwight D. Eisenhower. Nebraska's GOP senators made him a page at 14. While at the University of Virginia law school, he toured college campuses to debate professors on behalf of President Richard M. Nixon's 1972 reelection effort.

As a first-time candidate almost three decades ago, he crushed his opponent in the Mason District by placing himself firmly in the center.

"There is no liberal or conservative approach when it comes to neighborhood problems," Davis said at the time.

He announced yesterday that he will retire from Congress at the end of the year.

That message set the tone for his career in Fairfax County and Washington. Moderate, pragmatic and canny, Davis was willing to puncture party orthodoxy and reach across partisan lines to get things done.

"To me, Tom is what I think Republicans ought to be," said Fairfax Supervisor Michael R. Frey (R-Sully). "People who believe in limited government but who also believe that there is a role for government."

Critics on the left said his moderation was often equivocation and his bipartisanship a veneer that covered a voting record largely faithful to President Bush and the Republican leadership. His close relationship with Northern Virginia defense and tech contractors, who lavished him with campaign contributions while they prospered on his watch, also raised flags.

The right wing of his party viewed his rise with suspicion because of his left-of-conservative mainstream positions on issues including abortion and gun control.

But Davis saw himself as a peacemaker, a tiller of common ground, and he often was. As Fairfax County Board chairman in the early 1990s, he tried to steer a middle course on growth and land-use issues between politically potent developers and neighborhood groups.

When he worked for congressional passage of the D.C. Financial Control Board Act, which temporarily stripped the Washington of its self-governing powers, he called it "tough love" for the unraveling city government. He also worked for years, albeit unsuccessfully, to create a voting seat for the District in the U.S. House.

Davis has never disputed the idea that his compulsion to please stretches to a childhood spent as the family peacemaker, dealing with an alcoholic father prone to spasms of domestic violence and stretches in jail. A political life in the middle, although not nearly as turbulent, comes with its own risks.