Bucks County Republicans endorsed an incumbent-laden slate of candidates Thursday night in their quest to maintain control of county government despite a major shift in partisan registrations.

Leading the list were veteran County Commissioner Charles Martin and his newly appointed running mate, Commissioner Robert Loughery.

They will face a contested primary on May 22. Former commissioner Andrew Warren has vowed to stay in the race regardless of the party's endorsement.

Martin, 68, a former public affairs executive appointed in 1995, will be seeking his fifth consecutive four-year term. He has said this would be his last election run.

Loughery, 41, a businessman specializing in economic development, has been in office one month. The county's judges appointed him to complete the unexpired term of Jim Cawley, who was elected lieutenant governor in November.

Loughery urged the party to remind voters of the county governments' accomplishments, including a triple-A bond rating and five years without a tax increase, to maintain a GOP majority. "It's a story we need to tell the people as we face the many problems ahead of us," he told the gathering at Republican headquarters in Doylestown.

Democrats last week endorsed incumbent Commissioner Diane Ellis-Marseglia and Doylestown Borough Councilman Det Ansinn for the county's top government jobs. Republicans have held a 2-1 majority on the board of commissioners since 1988.

Democrats are hoping to capitalize on a 13,000-voter registration advantage built since the last commissioners' election, when Republicans had a 21,000-voter margin.

Also endorsed were incumbents Mary Smithson for clerk of courts, Joseph Campbell for coroner, and William Snyder for county treasurer.

The county's longest-serving row officer is not in the running. Register of Wills Barbara G. Reilly, first elected in 1975, has said she is stepping down for health reasons.

The Republicans endorsed Don Petrille of Perkasie to succeed her.

Reilly also is the subject of a criminal investigation by the District Attorney's office. Published reports have said a grand jury has been probing allegations that Reilly used public funds to pay employees for political work, which is illegal.

Less than two hours before the GOP gathering began, District Attorney David Heckler announced that he will hold a news conference Friday morning on the Register of Wills inquiry.

Contact staff writer Larry King at 215-345-0446 or lking@phillynews.com.