Virginia Attorney General-elect Mark Herring’s win will result in a special election to fill his seat in Virginia’s 33rd Senate district — a bellwether district spanning much of highly competitive Loudoun County. (Steve Helber/AP)

With the race for Virginia attorney general over, attention is rapidly turning to the state Senate seat that Attorney General-elect Mark R. Herring (D) will leave behind, a vacancy that could shift control of the evenly divided chamber.

State Sen. Mark D. Obenshain (R) conceded the attorney general’s race Wednesday after a recount widened Herring’s lead from 165 to 900 votes. On election night, it appeared to be the closest statewide election in Virginia history.

Herring’s win will result in a special election, probably in early January, to fill his seat from Virginia’s 33rd Senate District, a bellwether district that takes in much of highly competitive Loudoun County.

Three candidates are vying for Herring’s seat: Republican John Whitbeck, chairman of the state’s 10th Congressional District Republican Committee; Democrat Jennifer Wexton, a Leesburg lawyer who made an unsuccessful bid for Loudoun County commonwealth’s attorney in 2011; and state Del. Joe T. May, a longtime Republican lawmaker ousted in a primary this year. May recently cut his ties to the GOP and is running as an independent candidate.

Virginia Republicans, who dominate the state House of Delegates by a solid majority, view the race as a chance to take control of the state Senate. For Democrats, who swept three statewide offices this year, a victory in the special election is essential to having some control over the legislature. With a split chamber, Lt. Gov.-elect Ralph S. Northam would wield a tiebreaker vote for the Democrats.

J. Garren Shipley, spokesman for the Republican Party of Virginia, said Republicans have shifted their focus to special elections to fill Herring’s seat and Northam’s seat, in the 6th Senate District, although the latter is considered more of a Democratic stronghold.

“It would give us a much bigger voice in terms of what legislation would make it through” to the office of the incoming governor, Democrat Terry McAuliffe, Shipley said. “He would have to find common ground with the Republican caucuses in both chambers.”

Democrats are putting up a fight, with “a ton” of people on the ground knocking on doors and making calls, said the party’s Senate leader Richard L. Saslaw (Fairfax). Winning the Herring seat is critical, he said: “Otherwise, we don’t have control. It’s that simple.”

Holding the seat would make it easier “to keep the controversial bills and laws from happening,” Saslaw said. “At least the governor will have one body that is favorable to him.”

Shipley declined to discuss the party’s campaign and funding plans but said the state GOP “would make a concerted effort” to help both Republican candidates get elected.

Ashley Bauman, a spokeswoman for the Democratic Party of Virginia, said the Democratic Legislative Campaign Committee had spent more than $150,000 on the two special elections since Tuesday.

TV ads, radio ads and campaign mailers are in production, Bauman said. U.S. Rep. Gerald E. Connolly (D-Va.) has campaigned on Wexton’s behalf, and other top Democratic officials are expected to follow suit, she said.

I think you’re going to see from both sides that it’ll be all hands on deck,” she said. “This really is what Virginia’s looking at to hold a balance in the legislature. It’s the Senate that holds back all of the extreme social legislation — the voter ID bills, the [antiabortion] ultrasound bills. . . . It’s the Senate that’s our fail-safe. And that’s why this is so important for Virginia.”

Quentin Kidd, a political science professor at Christopher Newport University, said that although the 33rd District has taken center stage in Virginia politics, he doesn’t expect the outcome of race to have a particularly dramatic effect on McAuliffe’s plans.

“The Senate is by nature a more moderate chamber, and [McAuliffe] has not given me the impression that he’s going to be a really partisan governor,” Kidd said. “Nevertheless, if Democrats could have the Senate, I think they would feel more comfortable about things – then they could push a legislative agenda more easily. This race matters more for Democrats than it does for Republicans.”

But Republicans should be concerned, he said, about May’s well-known name being on the ballot. Even without the financial support of the state GOP, May poses a threat in a low-turnout special election, Kidd said, particularly against the hard-line conservative Whitbeck. A spokesman for May said Thursday that the candidate intends to continue caucusing with Republicans.

“If you’re a moderate Republican and Whitbeck turns you off, you’re likely to stay home,” Kidd said. “But if you’re a moderate Republican and you’ve got a conservative alternative, then you might still turn out and vote.”

Whitbeck, who secured his party’s nomination at a mass meeting Monday, made headlines in September after he told an anti-Semitic joke at a rally for GOP gubernatorial candidate Ken Cuccinelli II. Whitbeck later apologized for the remark, saying it was told in a moment of poor judgment and was not intended to give offense.

In recent days, Whitbeck has assailed Wexton over her “loyalty to anti-business special interests,” saying she would force workers to join unions. Wexton, in turn, has criticized Whitbeck as a tea party extremist who would push a “backward social agenda” over issues of most concern to Virginians.

May, meanwhile, has argued that he is the only “common-sense” candidate in the mix, touting his more than 20 years of experience in office and his background as an engineer and businessman.

A special election to fill Herring’s seat has not been scheduled by Gov. Robert F. McDonnell (R). Officials said it is likely to be held Jan. 7, the same date as the special election to fill Northam’s seat.