The Fairfax County primary to pick a Democratic challenger for the Board of Supervisors’ seat in the Braddock District turned into a nail-biter on Tuesday. There was such a narrow margin of victory that election officials will recount the vote Wednesday morning before declaring a victory, according to candidates and election officials.

After polls closed Tuesday night, Janet S. Oleszek, a former school board member, held a 42-vote lead over first-time candidate Christopher J. Wade. Oleszek once lost a legislative battle to then-Sen. Ken Cuccinelli by a razor’s edge

For a time — with just two precincts left to count – the lead was in Wade’s hands. With all 27 precincts reporting, however, Oleszek had 50.54 percent of the vote, compared with Wade’s 49.45 percent. There was one provisional ballot cast.

Edgardo Cortes, general registrar of the Fairfax County Office of Elections, said late Tuesday that although there is no provision in Virginia election law for an automatic recount, the Electoral Board will canvass, or reexamine, the vote Wednesday morning because of the intense interest in the Braddock District race. Ordinarily, a recount must be requested by a candidate. If the margin is less than 0.5 percent, the commonwealth would pay for the recount. If the margin is between 0.5 percent and 1 percent, the candidate who requests a recount must pay.

Late Tuesday, Wade called Oleszek to acknowledge that she appeared to be the winner, but both agreed that to postpone making a formal concession or claim of victory until the canvass. The winner will face Supervisor John C. Cook (R) this fall.

In the only other county-level primary, Republican Bill A. Cooper III, 55, of Fairfax Station, defeated H. Wes Kammerer, 73, of Centreville, to determine the challenger to Sheriff Stan G. Barry (D) in November. With results in from all precincts, Cooper had 11,511 votes, or 76.49 percent, compared with Kammerer’s 3,538, or 23.5 percent.