With all 19 precincts reporting, Kost led Barnes 60 percent to 40 percent.

Kost, 55, will face Republican Jeanna Bock in the November election.

In the other Democratic primary, District 2 incumbent Mike Cross appeared to hold off a spirited challenge from Jeffrey Starkweather. Cross led by 10 percentage points.

Cross will square off against GOP candidate Andy Wilkie in November.

Kost said she wants Chatham County government to be more responsive to residents' concerns and find more money for schools.

"We need to be much more collaborative," said Kost, chairwoman of the county's planning board.

"We've got to make schools our highest priority. We do that by finding money in the budget, by establishing goals and priorities."

Kost said she "knocked on a lot of doors" to spread the word about her candidacy. She cited her years of finance experience -- she used to work for the Federal Reserve and for Orange County as its budget director -- as being attractive to voters.

"Chatham County's at a crossroads," she said. "They need someone with budget and finance experience, and I bring that to the table."

Kost also has been active in working on plans to enact new subdivision and environmental ordinances, seen as key issues in rapidly growing Chatham.

Cross, 64, who has served one term, agrees that fixing the county's infrastructure is a top priority. He also said he wants to keep the issues of concern in his district at the forefront.

They're often pushed aside, he said, because his district has not seen quite the population boom as other areas of the county.

Starkweather's campaign mirrored Kost's, focusing on education, smart growth and a more open, accessible government.

Starkweather's chances might have been hurt by a third candidate, Armentha Lee Davis, who received about a quarter of the vote.