Pennsylvania- U.S. Rep. Don Sherwood, who had one of the safest seats in Congress until last year when he admitted to a five-year extramarital affair with a woman 35 years his junior, lost his bid for a fifth term yesterday.

The Republican representative from northeastern Pennsylvania was defeated by Democrat Chris Carney, a professor and lieutenant commander in the Naval Reserve who served as a military analyst at the Pentagon.

A 65-year-old married father of three who is considered a family-values conservative, Sherwood was sued in 2005 by his ex-mistress, who alleged that he physically abused her throughout their affair. He agreed to pay her about $500,000 in a settlement last year.

Carney targeted Sherwood with a hard-hitting TV commercial that featured a Republican voter from Sherwood’s hometown who says: “This incident with Don Sherwood just cuts right at the core values of our district.” Sherwood countered with an ad in which he said he was “truly sorry” for cheating on his wife, but denied ever abusing his mistress.

In western Pennsylvania, GOP U.S. Rep. Melissa Hart, who has served three terms, was defeated by Democrat Jason Altmire, a health-care executive. The suburban Pittsburgh district has more Democrats than Republicans, but voters supported President Bush in the last presidential election. Altmire, a political newcomer, was helped by a television advertising blitz and visits from national Democratic leaders. Like other Democratic candidates, he attacked his opponent for frequently voting with Bush.

One race not viewed as competitive involved Democratic U.S. Rep. John Murtha of Johnstown, a decorated Vietnam veteran who a year ago became a leading opponent of the war in Iraq. He easily defeated Republican Diana Irey, a Washington County commissioner. Murtha said he would run for House majority leader if Democrats took back the House.