Leesburg attorney Jennifer Wexton prevailed over Herndon Town Council member Sheila A. Olem in a firehouse primary election Saturday to select the Democratic nominee for the 33rd Virginia Senate District — the seat that would be vacated by state Sen. Mark R. Herring (D-Loudoun).

On Monday, Herring was declared the certified winner of the Nov. 5 Virginia attorney general race by the state Board of Elections. He defeated state Sen. Mark D. Obenshain (R-Harrisonburg) by 165 votes out of more than 2 million cast.

Despite the board’s certification of the election results, the board chairman also raised some concerns about the integrity of the vote tally in Virginia’s closest-ever statewide election, and a recount appears likely.

According to a statement by the Loudoun County Democratic Committee, more than 1,100 Democrats cast ballots at three locations in the 33rd district during Saturday’s caucus. Wexton received 729 votes to Olem’s 433, Democratic officials said.

Evan Macbeth, the committee chairman, said in the statement that he was pleased to declare Wexton the winner of the primary race.

She is “an amazing woman who will serve the people of Loudoun and Fairfax well,” Macbeth said. “Virginia can look forward to seeing her carry on Mark Herring’s example of common sense and pragmatic solutions in the Senate.”

J. Garren Shipley, a spokesman for the Republican Party of Virginia, said the GOP’s 33rd Senate legislative district committee would meet next week to decide a method of nomination and set a timeline for choosing a Republican nominee to fill Herring’s seat.

He said Republicans also plan to hold a similar meeting Dec. 17 in Obenshain’s district, allowing for the possibility that Obenshain might be declared the winner of the attorney general race following a recount.