Replacing Brown is likely to cost taxpayers several hundred thousand dollars. (Haraz N. Ghanbari/AP)

Brown resigned Wednesday, two days before he pleaded guilty to criminal charges of bank fraud and aiding and abetting illegal campaign spending.

The D.C. Board of Elections and Ethics officially declared a vacancy Monday morning and scheduled the special election to coincide with the general election day. The District charter gives the board leeway to co-schedule a special election with a previously scheduled general election. Otherwise, under the charter, the special election would have been set for Oct. 9.

Holding a stand-alone special election would have cost at least $850,000 and possibly more than $1 million, said board spokeswoman Alysoun McLaughlin. Adding the special election to Nov. 6’s festivities, she said, comes with a lesser cost that will vary based on the length of November’s ballot.

In a somewhat controversial decision, the board attorneys have ruled that while the general election and special election might be on the same day, they are in fact two discrete elections. The major consequence is that a candidate can run in both elections simultaneously. That’s an unprecedented circumstance in the District, where otherwise candidates may only appear once on a ballot.

McLaughlin said both board members present at the meeting — Stephen Danzansky and chairman Deborah K. Nichols — endorsed the separate-election finding, which she said was based on “a straight-forward reading of the language and the use of the world ‘election’” in city law.

A spokesman for D.C. Office of Campaign Finance said a candidate looking to run in both elections would have to establish a second committee for his or her chairman’s campaign. A candidate could raise the maximum legal amount from donors — $1,500 for a chairman’s race — who have also “maxed out” in the candidate’s other race, said the spokesman, Wesley Williams.

D.C. Council member Phil Mendelson (D-At Large), who is not up for re-election this year, has said he is likely to run for the seat. Vincent B. Orange (D-At Large), who is currently seeking re-election to his at-large seat, has also expressed interest.

Both are also vying to serve as interim chairman in a vote of council members set for Wednesday.

Candidates interested in appearing on the ballot can circulate nominating petitions as soon as Friday. They’ll have until Aug. 8 to collect signatures of 3,000 city voters.

The chairmanship, though only one vote of 13 on the council, carries great power to direct the city’s legislative agenda and its $10 billion budget.

The winner of the special election will complete Brown’s term, which runs through Jan. 2, 2015. Another chairman’s race will follow in 2014.

View Photo Gallery: Kwame Brown’s political career.