In this April 12, 2013, file photo, House Commerce, Justice, Science and Related Agencies subcommittee Chairman Rep. Frank Wolf, R-Va., listens during a hearing on Capitol Hill in Washington. Wolf says he will not seek another term after more than three decades in Congress. (Manuel Balce Ceneta/Associated Press)

A mainstream Republican backed by the party establishment faces a grass-roots conservative with a proclivity for controversial statements. As the GOP battles itself, Democrats hope to capitalize.

That scenario played out in Virginia in 2013 and in a handful of high-profile races around the country in recent elections. Now it may unfold again in Washington’s back yard, in the marquee race to succeed retiring U.S. Rep. Frank R. Wolf (R-Va.).

The battleground district, which stretches from McLean to the Shenandoah Valley and whose seat has not been vacant for more than three decades, has attracted a host of potential contenders from both parties.

Though the field remains in flux, the two most certain GOP candidates so far are Del. Barbara J. Comstock (Fairfax), who has deep ties to prominent state and national Republican figures, and state Sen. Richard H. Black (Loudoun), who is known for a conservative grass-roots following and a history of inflammatory remarks about social issues.

Local Republicans officials won’t decide until Jan. 23 whether to pick their nominee through a primary or a convention. The latter method yielded controversial lieutenant governor nominee E.W. Jackson last year, who beat several better-funded candidates at a convention and then got trounced by Democrat Ralph S. Northam in November.

Richard H. Black R-Loudoun, on the floor of the House of Delegates. (CINDY BLANCHARD/AP/Richmond Times-Dispatch)

Divisive primaries have also helped cost Republicans multiple Senate seats around the country in recent years, as conservative GOP candidates in Delaware, Nevada, Colorado, Indiana and a few other states beat establishment favorites and went on to lose in the general election.

A Comstock vs. Black matchup could draw notice beyond the borders of the 10th District.

“Among the hard-core grass roots, Comstock and Black are very well known and generate lots of passion,” said David Wasserman, who tracks House races for the nonpartisan Cook Political Report. “Both have worked their grass roots very hard over the years. Comstock in particular has long had an eye toward Congress.”

Comstock officially entered the race Tuesday morning, saying she was running “because I believe my strong record as a commonsense conservative leader is what is needed in Congress.” She said her priorities would include “repealing and replacing Obamacare” and keeping the military strong.

Comstock, who runs her own public relations firm and has served in the state House since 2010, has a wealth of personal and fundraising connections to draw on. She spent several years working in Congress — including as an aide to Wolf — and served as a Justice Department official in the George W. Bush administration.

Black has formed an exploratory committee and said Saturday he was “increasingly likely to enter the race.”

Black was elected to the Virginia Senate, representing parts of Loudoun and Prince William counties, in 2011, and he also served in the state House from 1998 through 2006. He has a strong core of conservative supporters, particularly in Loudoun.

But Black has also drawn negative attention. During House debate on a 2002 bill to lift Virginia’s ban on prosecuting spousal rape, Black said: “I do not know how on Earth you could validly get a conviction of a husband-wife rape where they’re living together, sleeping in the same bed, she’s in a nightie, and so forth, there is no injury, there’s no separation or anything.”

Black also made headlines in 2003, when he handed out plastic fetuses on the House floor during debate on an abortion bill. Last month, he told the Prince William Times that he believed polygamy was “just more natural” than homosexuality.

“When you talk about polygamy, at least it functions biologically,” Black told the paper.

The National Republican Congressional Committee likely won’t wade into a contested nomination race. But privately, national and state GOP strategists said they are aware of Black’s background and hope the nod goes to someone else.

Black dismissed the idea that his foes — from either party — would be able to use his past comments against him.

“I don’t think that those issues are likely to be the predominant ones in the race,” Black said. “The Democrats have sort of a tried-and-true routine of trying to make social issues always the most prominent thing.”

Mitt Romney narrowly won the district in the 2012 presidential race, and Ken Cuccinelli II did the same in the 2013 governor’s race, even as both Republicans lost statewide. So the GOP begins any contest with a slight edge.

“A candidate like a Dick Black would enhance Democrats’ chances of winning, but it’s not guaranteed,” Wasserman said.

The GOP field may well be larger than just two people. Frederick County Board of Supervisors chairman Richard C. Shickle said Monday he is “likely to run.” Several other Republicans are considering entering the race, including Winchester attorney Beau Correll, former 11th District candidate Keith Fimian, Del. James M. LeMunyon (Fairfax), Del. J. Randall Minchew (Loudoun), and former Prince William County Board of Supervisors member John Stirrup.

Artur Davis, the former Democratic congressman from Alabama who is now a Republican living in Northern Virginia, recently ruled himself out of the race, saying “the process of competing for a partisan nomination wouldn’t exactly allow me to run a campaign focused on building common ground.”

Another potential candidate, home-schooling advocate and Patrick Henry College chancellor Michael Farris, said he is “highly unlikely” to run.

The entire GOP field is relatively conservative. The Family Foundation, a Richmond-based conservative advocacy group, gave Black a 100 percent “pro-family” score for his 2012-13 voting record. Comstock and Minchew both scored 89 percent, while LeMunyon’s rating was 74 percent.

Most members of the 10th Congressional District Republican committee, which will decide the nomination method, are believed to prefer a convention. But some Virginia Republicans worry that conventions tend to favor the most conservative — not necessarily the most electable — candidates, like Jackson.

Democrats in the district also face a choice. Their current field includes Fairfax County Board of Supervisors member John W. Foust, Fairfax lawyer Richard Bolger and Leesburg architect Sam Kubba.

Foust was the favored candidate of national Democrats before Wolf announced his retirement. Now the outlook is more uncertain, and Karen Kennedy Schultz, a Shenandoah University professor who ran an unsuccessful bid for state Senate in 2007, is believed to be considering the race. Schultz did not respond to a request for comment.

Schultz is getting encouragement from Emily’s List, the group that backs pro-abortion rights women candidates. Virginia’s congressional delegation is all-male.

Foust has locked up endorsements from several Virginia Democrats, including U.S. Rep. James P. Moran Jr. and state Senate Democratic leader Richard L. Saslaw (Fairfax). Many of them backed Foust before Wolf’s retirement made it an open-seat race.