Fairfax County Board of Supervisors chairman Sharon S. Bulova (D) has piled up a war chest nearly three times the sum raised by her Republican challenger, according to campaign finance reports posted Tuesday by the nonpartisan Virginia Public Access Project.

Bulova has raised $178,133 since Jan. 1, compared with the $64,411 collected by Michael “Spike” Williams, VPAP figures show.

Bulova, who started the year with nearly $91,000, had a balance of $209,981 as of June 30, compared with $40,542 for Williams.

Among the biggest donors to Bulova’s campaign are the firefighters’ union, real estate concerns and a former AOL executive who is registered as a Republican. Since Jan. 1, Fairfax County Professional Fire Fighters and Paramedics, which is Local 2068 of the International Association of Firefighters, gave $20,000; McLean-based Tysons West Assemblage also gave $20,000; and a limited partnership named 8500 CDC gave $15,000. George Vradenburg III, a former executive at America Online and philanthropist who lives in the District of Columbia, gave $10,000. Vradenburg is registered as a Republican in the District of Columbia, according to voter registration records.

Williams’ largest donors include people in the real estate business, Fairfax County supervisor Michael R. Frey (R-Sully), who gave $1,000, and Marianne L. Horinko, who at one time considered running as a Republican for the Board of Supervisors’ chairmanship and filed papers to create a campaign committee in 2010. Horinko, who is president of an the Horinko Group environmental consulting firm, donated $9,000.

Williams, who co-owns the Williams Realty Group with his wife, ran unsuccessfully as an independent against Hunter Mill District supervisor Catherine M. Hudgins in 2007.

The newly reported figures from VPAP come as Williams was scheduled to hold a fundraiser Tuesday evening with Rep. Frank Wolf. As it turned out, Wolf could not attend because of a vote in Congress, but he called in and spoke to the attendees by telephone.

Meanwhile, Will Radle Jr., an independent candidate, has raised $5.

This report has been updated.