The race to represent Northern Virginia's 11th Congressional District features a five-term Republican incumbent who prides himself on delivering for his constituents and a Democratic newcomer who hopes to replace him, in part by riding on John F. Kerry's coattails.

Democrat Ken Longmyer, 66, a retired foreign service officer, wrote himself in on the ballot on Election Day two years ago when he saw that Rep. Thomas M. Davis III had no party opposition. He pledged to challenge Davis this year if no other Democrat stepped forward. Although fundraising has been lopsided in favor of Davis, the challenger has run a spirited campaign, stressing Bush administration policies he disagrees with and calling Davis a conservative in moderate's clothing.

Davis, 55, is one of Northern Virginia's best-known political figures. He has been reelected by wide margins in the Republican-leaning district. Democrats did not field anyone against him in two of the last three elections. But he says he is taking nothing for granted in his race against Longmyer.

He has crisscrossed the district's neighborhoods of central Fairfax and western Prince William counties, squeezing in dozens of appearances, from a day-care center to a high school homecoming parade.

Davis points to a busy term serving as head of the House Committee on Government Reform, the starting point for several new laws that affect thousands of his constituents: government workers and government contractors.

Davis will also face Green Party candidate Joseph P. Oddo, a freelance writer and sales consultant, on Tuesday.

Davis and Longmyer have debated several times, diverging on issues such as the war in Iraq, the Bush tax cuts and the new Medicare prescription drug plan, which Davis supported and Longmyer criticizes as inadequate. Longmyer has attacked Davis for voting with the leadership of the GOP-controlled House of Representatives on many issues, votes he said do not represent the more moderate views of the 11th District.

"Half of my campaign is to say, 'Do you really know Tom Davis?' " Longmyer said. The other half is to appeal to voters who support Kerry, the U.S. senator from Massachusetts who is the Democratic presidential nominee.

Davis notes that he has broken with the GOP majority on social issues such as gun control, stem cell research and abortion rights, which he supports, as well as some environmental issues, including oil drilling in the Arctic National Wildlife Refuge, which he opposed. He says Longmyer has not shown a strong record of involvement in his community. "If you're a liberal Democrat and you want a Kerry clone, he's your guy," Davis said, calling himself "a prolific legislator and a doer."

Davis lives in Vienna, Longmyer in the Sleepy Hollow area outside Falls Church. While Davis has been serving constituents in politics for 25 years, first as a Fairfax County supervisor and then as board chairman, Longmyer has served as a diplomat in Israel, Sweden and Germany.

Before his retirement from the State Department last spring, Longmyer held several domestic posts. He was an adviser on Bosnian peace implementation in the Clinton administration and more recently was special assistant on U.N. counterterrorism and on homeland security.

Davis, meanwhile, was named to head the Committee on Government Reform after a four-year run leading the House Republicans' fundraising committee.

Davis stresses his work securing federal transportation money to rebuild the Woodrow Wilson Bridge, widen Route 123 and launch engineering work for an extension of Metrorail to Reston.

He also notes that he helped push legislation through Congress giving federal workers a pay raise. And he cites his successful efforts to help close the former federal prison at Lorton and transfer 2,300 acres to Fairfax for open space, a school and a housing development. He highlights those accomplishments in a television ad running in Northern Virginia markets.

Longmyer said he would fight for more generous prescription drug benefits for the elderly, a reduced federal deficit, stronger laws to protect the environment and full funding of the No Child Left Behind law, Bush's signature education program.

He has criticized Davis for taking campaign contributions from drug companies as he voted for the new law expanding Medicare coverage of prescription drugs, which does not allow the government to negotiate lower prices with the industry. Davis said he believes that free market forces are the best way to keep prices low.