A Northern Virginia lawmaker is the first Republican delegate to face a primary challenger since 2005, a reflection of a state party that has fragmented since the GOP-controlled General Assembly passed a tax hike to pay for roadwork.

Del. Joe May, R-Leesburg, will square off in a June 11 primary against Dave LaRock, a small-businessman and first-time political candidate from Loudoun County. In the last three House elections, not a single Republican was challenged and so far May, 75, is the only lawmaker with an opponent.

LaRock's entry into the race comes after May played helped negotiate a transportation package that raised $880 million a year through a series of tax increases. May, whose district includes parts of Loudoun and Clark counties, was one of 43 Republicans to vote for the bill, which is awaiting action by Gov. Bob McDonnell.

"I'm not surprised to have someone running against me," May said. "I still think it will turn out that at least a majority support addressing our long-term transportation funding problems and its equally likely that there's a small group that isn't happy with any way we approach it."

LaRock, 56, was gearing up for a run before the vote on transportation, but he said he hopes to capitalize on the anger the tax increases have sparked in conservative circles.

"The intensity has turned up with this transportation vote that just took place," LaRock said. "We hope that continues and we can harness that into a strong campaign."

But while conservatives animosity toward fellow Republicans is high, it might be too late to launch a statewide effort to challenge every delegate who voted for the transportation bill, said John Jaggers, director of operations for the Northern Virginia Tea Party. The deadline to register for the primary election is March 28.

"What will likely happen is they will be picked off one at a time over several cycles," Jaggers said. "This will not be forgotten and a lot of people will be very angry about it."

In the hours before the vote on the transportation bill, House Speaker Bill Howell told Republican lawmakers not to be worried of losing an election because of the issue. Still, nearly every GOP candidate for statewide office, including gubernatorial nominee Attorney General Ken Cuccinelli, has publicly bashed the bill.

Concern of a divided GOP has left party leaders scrambling to defend a popular governor still in power and the Republicans who voted for a tax hike while preparing for a new wave of much more conservative candidates. State party Chairman Pat Mullins wrote on his Facebook wall Tuesday: "We need to be united as a party and focused on winning this fall."