Veteran Rep. David Dreier, one of California's most influential Republicans in Congress, announced Wednesday that he won't be running for reelection, perhaps the biggest casualty of the state's first-ever citizens-drawn political map, which cast him into a politically inhospitable district.

Dreier is the sixth California House member to announce his retirement when his term expires, further shaking up a delegation that has built up clout on Capitol Hill because of its stability over the years.

Dreier, chairman of the House Rules Committee, made the announcement on the House floor, citing Congress' "abysmally low approval rating."

INTERACTIVE: California's citizen commission district maps

"The American people are asking for change in Congress," he said.

Dreier's retirement is not a surprise, given the challenges he faced in winning reelection in a redrawn district.

But his decision perhaps changes the face of the state's delegation more than any of the others because of his position as the first Californian to chair the committee that decides which measures go to the House floor.

Elected to Congress in the 1980 Ronald Reagan landslide, the 59-year-old congressman is also head of the California GOP delegation.

Dreier's San Dimas home was placed in a Latino-majority district where Democrat Barack Obama defeated Republican John McCain in the last presidential race.

Others who have announced plans to retire are fellow Republicans Jerry Lewis of Redlands, Elton Gallegly of Simi Valley and Wally Herger of Chico as well as Democrats Dennis Cardoza of Atwater and Lynn Woolsey of Petaluma. Democrat Rep. Bob Filner is running for mayor of San Diego.

Dreier supported a petition drive to overturn the redistricting plan, drawn for the first time by citizens instead of politicians, but it never came to pass because his California Republican colleagues were divided over the idea.

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-- Richard Simon in Washington

Photo: Rep. David Dreier during a July 2011 congressional hearing in Washington. Credit: J. Scott Applewhite / Associated Press