Democrats on Tuesday kept their hold on a Brockton-based state Senate seat, with state Rep. Michael Brady beating state Rep. Geoff Diehl.

Diehl, R-Whitman, conceded to Brady, D-Brockton after the polls closed. A third candidate in the race, Anna Ruduc, ran as an independent.

The late state Sen. Thomas Kennedy, who died in June, had held the seat since 2009. The district includes Brockton, Halifax, Hanover, Hanson, Plympton and Whitman, and parts of East Bridgewater and Easton.

The special election to replace Kennedy drew the attention of the state Democratic Party and the state Republican Party, and their heavyweights. Gov. Charlie Baker, R-Swampscott, backed Diehl, while U.S. Sen. Elizabeth Warren, D-Cambridge, supported Brady.