Fairfax County election officials plan Wednesday to recount the vote in the Democratic primary for the Board of Supervisors’ seat in the Braddock District because of the tiny lead held by Janet S. Oleszek over Christopher J. Wade.

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

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 to postpone making a formal concession or claim of victory until the recount. The winner will face Republican incumbent John C. Cook.

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.

A sliver of Fairfax’s registered voters headed to the polls for the primaries Tuesday. And that was before a 5.8-magnitude earthquake that was centered in Mineral, Va., rattled the East Coast about 2 p.m. The quake diminished turnout further, officials said, but voting continued with paper ballots at some makeshift polling places set up outside buildings that had closed after the quake.

Oleszek, 64, entered the race with some name recognition. Having lived in Fairfax for nearly four decades, she won election to the School Board in 2003 and lost a close race against Republican Cuccinelli in 2007.

Wade, 38, had the backing of several elected officials, including Board of Supervisors Chairman Sharon Bulova (D). Wade, a father of three, is a businessman and an adjunct instructor at George Mason University. His campaign was dogged by accusations that he was not really a Democrat, owing to his participation in some GOP primaries. But Wade cast himself as an independent.