The announcement triggers an automatic March 8 primary for the Sacramento-area seat that Matsui held for 26 years. If a candidate wins a majority in the primary, the May election will not be necessary. Otherwise, the top vote-getters from each party will square off May 3.
Matsui's widow, Doris, a longtime Washington lobbyist who worked in the Clinton administration, has said she plans to run. State Sen. Deborah Ortiz (search), a Sacramento Democrat, is also considering a bid.