WASHINGTON (AP) — Voters are casting their ballots in a scandal-marred race for District of Columbia mayor.

Early voting began March 17 for the district’s April 1 primary.

Mayor Vincent Gray is seeking a second term amid allegations by federal prosecutors that he knew about an illegal, $668,000 “shadow campaign” waged on his behalf when he ran for mayor in 2010. Gray has not been charged with a crime.

The mayor faces seven challengers, including four D.C. councilmembers: Muriel Bowser, Jack Evans, Vincent Orange and Tommy Wells. Councilmember David Catania, an independent, will run against the primary winner.

Voters began casting ballots starting March 17 at the building that houses the Board of Elections. More locations will open starting March 22.