Matsui died of complications from a rare disease Saturday night at Bethesda Naval Hospital outside Washington, D.C., his family said Sunday. He was 63.
In a statement, President Bush called Matsui "a dedicated public servant and a good and decent man who served with distinction" in Congress, adding, "Laura and I send our prayers and condolences."
Matsui was an attorney who became a City Council member in 1971 before winning election to the capital city's solidly Democratic fifth congressional district in 1978. He juggled political and policy roles during more than a quarter-century in Congress, most recently serving as chairman of the Democratic Congressional Campaign Committee where he headed the party's unsuccessful effort to regain control of the House.
He also was the third-ranking Democrat on the powerful House Ways and Means Committee, where he was his party's point man on Social Security legislation.
In a statement announcing Matsui's death, his office disclosed that the congressman had been diagnosed several months ago with myelodysplastic disorder, an often-fatal form of bone marrow cancer. The congressman's family said he entered the hospital on Dec. 24 with pneumonia.
U.S. Sen. Barbara Boxer called herself "shocked and despondent" over Matsui's death, saying in a statement, "He has been part of my political life for more than 20 years, and he represented the best in politics."
Matsui was born in 1941. The following year, his family was among the Japanese-Americans forced into internment camps during World War II. Decades later, he helped pass legislation which apologized for the internment policy and provided compensation for the survivors. In a 1988 speech to his congressional colleagues, Matsui said he was motivated by "the tears and painful remembrances of internees."
U.S. Sen. Dianne Feinstein called Matsui as "a master of balanced, practical public policy" and praised his successful efforts to seek legislative redress for other Japanese-Americans who had been interned during War II.
Former President Clinton and his wife, U.S. Sen. Hillary Rodham Clinton, said in a statement, "Bob Matsui leaves behind a rich legacy of service that improved the lives of his own constituents, all Americans, and people throughout the world."
California's Republican governor, Arnold Schwarzenegger, also praised Matsui in a statement, saying, "Today, all Californians mourn the loss of this tremendous individual and man of integrity." Schwarzenegger will call a special election for a new representative in his Sacramento-area district.
Matsui was recently re-elected with ease to his 14th term. His wife, Doris, was until 1998 a deputy director of public liaison in the Clinton White House. He is also survived by a son, Brian.
In his hometown Sunday, Sacramento Mayor Heather Fargo described Matsui as "our voice, our advocate, our leader" in ensuring federal support for flood control, light rail, transportation, housing and parks projects in the city of 418,000 people.
"His loss obviously goes well beyond Sacramento, but I think it's felt strongest here," she said.
Matsui generally supported Democratic legislation, but his support for global trade legislation put him at odds with members of his party on some high-profile measures.
As senior Democrat on the subcommittee on Social Security, Matsui gave every impression during the final few weeks of his life of being eager to lead the opposition to Bush's plans to establish personal retirement accounts as part of a general overhaul of the program.
"With the passing of Bob Matsui, our country has lost a great leader and America's seniors have lost their best friend in Congress," House Democratic Leader Nancy Pelosi, a friend and fellow Californian, said in a statement.
Incoming Senate Democratic Leader Harry Reid of Nevada recalled Matsui as "a champion for the underdog who was the same kind, gracious man no matter how far he rose in Congress and in life."