Phillip D. Bissett, 46, a former state delegate and Mayo resident, jumped out to an early lead against Tom Angelis, 56, a teacher and former county recreation and parks director from Davidsonville.
With about 40 percent of precincts reporting, Bissett was leading with more than 60 percent of the vote. Angelis had around 40 percent.
"I don't worry about looking at my numbers," said Angelis, who spent the evening with other Republicans at Kaufmann's Tavern in Gambrills. "I'm only concerned when the final numbers come in."
The winner will face County Executive Janet S. Owens -- a Democrat from Millersville who in 1998 became the first woman to win the county's highest elected seat -- in the Nov. 5 general election. Owens was unchallenged in the primary.
The primary race between Bissett and Angelis was civil at first but disintegrated into a smear contest as the summer wore on. Bissett accused Angelis of being a "me-too" candidate who lacked originality. Angelis charged that Bissett offered to find him a lucrative job in state or county government if he would bow out of the race.
Angelis and Bissett also attacked Owens, 58, a former Orphans' Court judge and director of the county Department of Aging, who they said hasn't done enough to stem development, preserve farmland and open space, or improve student achievement.
The Owens camp has been quick to dismiss such charges. Campaign brochures promote Owens' preservation record -- more than 4,000 acres has been set aside in permanent development easements since 1998 -- as well as her efforts to hire more teachers and reduce class sizes.
The months leading up to the primary race were subdued compared to years past -- four years ago County Executive John G. Gary was challenged by Council member Diane R. Evans, a Republican-turned-Democrat, and trounced by Owens in the general election -- largely because Owens and a majority of council members were unchallenged.
But Bissett, who served in the General Assembly from 1991 to 1998, didn't waste time. He spent most of the summer finding fault with Owens and her administration, criticizing what he called her lack of management skills and unbalanced land preservation and development programs.
Bissett has criticized Owens for using county police officers as personal security guards and chauffeurs. Bissett, who has a license to carry a concealed weapon, has said he would not need a bodyguard. Owens security detail has costs taxpayers about $500,000 during the nearly four years that she has been in office.
Owens has spent a relatively quiet summer, focusing instead on winning passage of legislation necessary for the redevelopment of the former David Taylor Research Center. The Owens campaign, led by Owens' husband, Baltimore attorney David M. Sheehan, has called Bissett's attacks as "misinformed."
Whereas Owens was the underdog four years ago when she took on Evans in the primary and Gary in the general election, she has been blessed this time with many endorsements and a fund-raising campaign that has exceeded expectations. She had about $230,000 in the bank at last count, significantly more than either Bissett or Angelis.
Sun staff writers Gabriel Baird and Julie Bykowicz contributed this article.