North Stonington — The third time wasn’t the charm for petitioning first selectman candidate Bob Testa, who lost again Tuesday to longtime incumbent and three-time rival Nicholas H. Mullane II in an 838 to 702 vote.

With the second-highest vote count of the five Board of Selectmen candidates, Testa will serve as a selectman along with incumbent Mark Donahue, who held his seat as an uncontested Democrat with 348 votes.

Mullane’s running mate, Republican Brett Mastroianni — a local business owner who serves on the Economic Development Commission — came in just one vote shy of Testa. Registrar of Voters Marilyn Mackay said there will likely be an automatic recount and is waiting to hear back from the Secretary of the State’s office.

“One vote is tough,” Mastroianni said. “I’d rather have lost by 50.”

Mullane has served as first selectman nearly continuously since 1983, booted down to a selectman seat from 1995 to 1997. This will be his 15th term.

Testa, chairman of the Board of Education, challenged Mullane as a petitioning candidate in 2007. Testa won the town Republicans’ endorsement in 2011 before losing to Mullane in a September primary. He ran and lost as a write-in.

Mullane called it a “strange ending” to the election and expressed disappointment that he would not be working with Mastroianni.

“It’s always nice to win, but to some degree, it has a shallowness to it,” he said. “One vote is difficult to accept.”

Economic development was the issue du jour this election season, as the town wraps up its Plan of Conservation and Development in an effort to bring sorely needed businesses in while maintaining its prized rural character.

Testa and running mate Tim Pelland, who serves on the Affordable Housing Commission, campaigned on bringing new ideas to counteract stale leadership and the town’s “regression,” focusing on streamlining town and school resources and bringing businesses to vacant buildings.

Mullane emphasized his decades of experience and wealth of local and state government knowledge, speaking of plans for public water and sewer that he said would make the town more business-friendly.

During the race, Testa criticized Mullane’s “controlling” leadership style, while Mullane repeatedly said that no challenger during his tenure has been better qualified.

Testa said he was “a little baffled,” claiming he didn’t speak to a single person in town during the campaign who wasn’t critical of Mullane. Despite the results, Testa said he is unconcerned about the possibility of a recount and vowed to “serve the people” and hold Mullane accountable.

“I’m not a puppet of Nick Mullane,” Testa said.

Mullane echoed Testa’s promise to serve the interests of residents.

“I know we’ll all just pull together and work for the town,” he said.

Of the town’s 3,775 registered voters, about 42 percent cast ballots Tuesday.

a.isaacs@theday.com