Former governor Edmund G. "Jerry" Brown Jr., a member of California's best-known political family, announced he will resign as state Democratic Party chairman to run next year for the Senate seat being vacated by Alan Cranston (D).

"I think I made a significant contribution in rebuilding the party, and I can best serve to inspire voters as a candidate," said Brown, who will step down at the party's annual convention March 3.

Vowing a grass-roots campaign emphasizing political reform, populist economics and environmental issues, Brown said, "I'm going to run in a different way," he said. "I'm going to spend more time talking to regular voters than going to $50,000 cocktail parties."

Other Democrats who have announced plans to run for the Senate are Reps. Robert T. Matsui of Sacramento and Barbara Boxer of San Rafael. Also considering the race are Controller Gray Davis and Rep. Mel Levine of Los Angeles.

Brown was defeated by Pete Wilson (R), now governor, when he ran for the Senate in 1982 after serving two terms as California's chief executive. At the time Brown was viewed as unconventional by many Democratic leaders, but he has worked at building party support in his role as chairman.

Brown has been criticized, however, for the weak showing of the Democratic turnout efforts in last November's gubernatorial election, where Wilson defeated former San Francisco mayor Dianne Feinstein (D). She has since announced that she will seek the other Senate seat on the California ballot next year, running for the remaining two years of Wilson's Senate term against Republican John Seymour.

Brown is the son of Edmund G. "Pat" Brown, who served two terms as governor before he was defeated by Ronald Reagan in 1966. Last November, Pat Brown's daughter Kathleen was elected state treasurer.