HONOLULU — A bit more than 28 percent of the 317,337 ballots mailed to registered voters in the special election for Hawaii's vacant congressional seat have been returned so far.

Office of Elections spokesman Rex Quidilla said Monday that an estimated 90,000 ballots have been received.

The all-mail election will determine who represents the 1st Congressional District for the remainder of the current term, which ends in January.

Ballots are due at the Office of Elections or the state Capitol by 6 p.m. on May 22.

Ballot tabulating begins on May 19 but results will not be released until after 6 p.m. on May 22.