Democrats will hold a “firehouse primary” Saturday to determine the Democratic nominee for the 33rd Virginia Senate district — the seat that would be vacated by state Sen. Mark R. Herring, who currently holds a lead of 164 votes over Republican Mark D. Obenshain in the race for Virginia attorney general.

The results of the attorney general election will be certified next week, and a recount appears certain; Obenshain has said he will not yet consider conceding to Herring, and both candidates have announced transition teams.

The firehouse primary is open to all Democrats who are registered voters living in the 33rd Senate district. Voters will choose between two Democratic candidates: Leesburg attorney Jennifer Wexton and Herndon Town Council member Sheila A. Olem.

Republicans have not yet announced a candidate in the district, though 10th District Republican Committee Chairman John Whitbeck has been considered a possibility. Whitbeck drew condemnation from Democrats and Republicans alike after he told an anti-Semitic joke at a rally for Republican gubernatorial candidate Ken Cuccinelli II (R) in September — a remark for which Whitbeck later apologized.

There is also speculation that Del. Joe T. May (R-Loudoun) could join the race as an Independent candidate. May, a 20-year incumbent in the Virginia House’s 33rd district, was defeated in a startling upset in the June Republican primary by Dave LaRock, a hard-line conservative newcomer.

The Democratic primary voting will occur at three locations on Saturday: Herndon Community Center, meeting room 3, in Herndon; Cascades Library, conference room B, in Potomac Falls; and Rust Library, group study room, in Leesburg, according to a statement by the Loudoun County Democratic Committee.