The Democratic field has become clearer and the electoral calendar has been compressed in the battleground contest to succeed retiring U.S. Rep. Frank Wolf (R-Va.).

Democrats in Wolf’s 10th district decided over the weekend to pick their nominee at an April 26 convention, and Fairfax County Board of Supervisors member John Foust appears increasingly likely to get the nod. Republicans had previously decided to hold a party canvass — otherwise known as a firehouse primary — on the same date, and Del. Barbara J. Comstock (Fairfax) is seen as the frontrunner in a large GOP field.

Both parties are eyeing the seat of the veteran Wolf, who plans to leave office after more than three decades. His district stretches from McLean all the way to the West Virginia border and has been extremely competitive in recent statewide races.

Foust is one of four Democrats currently in the race, along with Fairfax lawyer Richard Bolger, Leesburg architect Sam Kubba and Marine Corps veteran David R. Wroblewski. But Foust has a big fundraising advantage and has attracted the endorsements of several local officeholders.

More importantly, key Democrats in the district do not expect Shenandoah University professor Karen Schultz, a potentially formidable challenger, to run. Schultz did not respond to several requests for comment.

To pick their nominee, 10th district Democrats will hold a series of small caucus meetings across the district, where delegates will be chosen who support the various candidates. Then those delegates will gather at the April 26 convention to vote for the final choice.

Foust said in a statement that he was prepared to compete in any kind of nomination method, but “I do believe a convention and local caucuses will be a real test of our campaign’s organizational strength and our supporters’ enthusiasm.”

Republicans, meanwhile, will hold a firehouse primary, which differs from a regular primary in that it will feature only a handful of polling places and will be run by the party rather than the state.

The Virginia GOP has been criticized before by Democrats for holding conventions to pick nominees, and 10th district Republican committee chairman John Whitbeck said Democrats were being hypocrites.

“It is an outrage that Democrats would seek to portray Republicans as exclusionary and only concerned with purity and then turn around and choose a convention themselves,” Whitbeck said.

Charlie Jackson, Whitbeck’s Democratic counterpart, said their convention would be different from the ones Republicans typically hold because they will be preceded by smaller caucus meetings.

“I think they pick conventions to nominate the most extreme tea party candidates they can,” Jackson said.