With all precincts reporting, Eric Cantor, a member of the state House of Delegates, had 20,902 votes, just over 50 percent, while state Sen. Steve Martin had 20,637 votes, just under 50 percent.
"I spoke to Eric Cantor and in that conversation I let him know that I offered my congratulations pending that recount," Martin told cheering supporters.
Cantor, who had Gov. Jim Gilmore's endorsement, had questioned Martin's votes on legislative pay and expenses. Martin raised issues about Cantor's family's dealings in real estate.
Elsewhere on a day of primary and runoff elections in five states, an open House seat from South Carolina drew six GOP candidates, while two Arkansas Democrats were in a runoff for a House seat. Virginia also saw a contentious fight for a second open House seat.
Cantor will face school superintendent Warren Stewart, whom Democrats nominated at the last minute on Monday in the race to fill the seat of GOP Rep. Thomas J. Bliley, who is retiring after 20 years.
In an eastern Virginia House race, Jo Ann Davis, a member of the House of Delegates, defeated businessman Paul Jost for the GOP nomination, even though he spent nearly $1 million of his own money, more than three times the combined total of all four of his opponents.
With all precincts reporting, Davis had 14,263 votes, or 35 percent, to Jost's 12,155 votes, or 30 percent.
She will face former Fredericksburg mayor Lawrence Davies, a Democrat, in the November race to replace retiring GOP Rep. Herbert H. Bateman.
Jost, who also had the governor's endorsement, was attacked by other candidates who said he supported abortion and gay rights, and critics mailed out fliers with a photo of two men kissing, labeled "Paul Jost's Vision of Virginia." Jost said he is opposed to abortion except in cases of rape, incest or when the woman's life is in danger. On gay rights, his campaign said Jost opposes all forms of discrimination.
The biggest seats up for election Tuesday went unchallenged. No primary opponents emerged for two-term Democratic Sen. Charles Robb of Virginia, freshman GOP Sen. Olympia Snowe of Maine and Democratic Sen. Kent Conrad of North Dakota, seeking a third full term. Even North Dakota's seat for governor, open because Republican Ed Schafer chose not to seek a third term, went without a primary fight.
A crowded South Carolina race went to a runoff, with state Rep. Henry Brown taking 44 percent of the vote. His nearest opponent, former state transportation chairman H.B. "Buck" Limehouse, got 33 percent, after Limehouse outspent Brown by nearly 3-1.
The seat, in a coastal district, is held by GOP Rep. Mark Sanford, who is sticking to a campaign pledge to serve jut three terms. Democrat Andy Brack, a former reporter and spokesman for Democratic Sen. Ernest Hollings, is unopposed in the primary.
And in a South Carolina primary that will essentially determine the general election winner, first-term GOP Rep. James DeMint easily defeated Frank Raddish. Democrats did not run a candidate in the heavily GOP district.
With 96 percent of North Dakota precincts reporting, a majority was voting to keep the state treasurer's post. The proposal to eliminate it had drawn criticism from state treasurers around the nation.
And early returns from six western counties showed a mixed response to a proposal to set their clocks ahead to Central time and join the eastern part of the state. Two counties endorsed the plan, while results were pending from the others. Whatever the vote, county and federal officials must agree on any change. Several other counties aren't considering a move from Mountain time.
In a runoff for the Democratic nomination for an Arkansas House seat, state Sen. Mike Ross defeated former TV reporter Dewayne Graham 58 percent to 42 percent. Ross will face GOP Rep. Jay Dickey in the fall.