Del. Robert G. Marshall is jumping into the Republican race to succeed retiring U.S. Rep. Frank Wolf (R), adding a prominent conservative name to a crowded Northern Virginia field.

Marshall is at least the seventh GOP candidate for Wolf’s district, a battleground seat which stretches from McLean to the West Virginia border and also dives south to take in a portion of Prince William County. Del. Barbara Comstock (Fairfax), a proven fundraiser with the backing of many figures in the Republican establishment, appears to be the front-runner.

Marshall, who represents Prince William, joins several candidates now angling to portray themselves as the best conservative alternative to Comstock. He has served in the General Assembly since 1992, making his name as a vocal opponent of abortion and gay rights, among other issues.

Marshall said Wednesday that Comstock has failed to push conservative legislation in a host of crucial areas.

“Nothing on marriage, nothing on protecting the right to life, nothing on the Second Amendment,” Marshall said in an interview. “I’m aggressive on those things. There’s a difference between someone who leads on these things and someone who just votes on them.”

Comstock adviser Ray Allen said Comstock is a “solid conservative,” and said such tactics were the reason why Marshall lost bids for the Republican nomination to the U.S. Senate in 2008 and 2012.

“Republicans and conservatives are tired of Bob’s constant attacks on fellow Republicans, [and his] always trying to tear down good people and never standing for anything positive is getting tiresome,” Allen said. “This is why he keeps losing.”

Marshall said it’s time for him to move from being a Richmond legislator to being one in Washington, where he can take on President Obama more aggressively than House Speaker John Boehner (R-Ohio) has, particularly on Obama’s use of executive actions to make changes to the Affordable Care Act.

“What has Boehner done to stop it? If he’s done something, he’s done it in the closet. I can’t see it. This is destroying representative government,” Marshall said.

Marshall noted that he has won a dozen elections in Northern Virginia, and has represented parts of both Loudoun and Prince William that are currently in Wolf’s district.

Marshall’s outspokenness has been the source of controversy before. In 2010, he said that women who have abortions are more likely to have children with disabilities “[b]ecause when you abort the firstborn of any, nature takes its vengeance on the subsequent children.”

Along with Marshall and Comstock, the Republican field to succeed Wolf includes former Pentagon official and lobbyist Howie Lind; Richard C. Shickle, chairman of the Frederick County Board of Supervisors; Stephen Hollingshead, an official in the administration of President George W. Bush; former congressional aide Rob Wasinger; and Marc Savitt, head of the National Association of Independent Housing Professionals.

Republicans will choose their nominee April 26 in a party canvass — otherwise known as a firehouse primary. Democrats will pick their nominee the same day at a convention, with Fairfax County Board of Supervisors member John Foust considered the favorite for their nod.