A Democrat, Clayton Klein was first elected to the Oregon Legislature in November 1976, taking office in January 1977.
During his first term, he argued in favor of legislation, which ultimately did not pass, that would have lowered the legal drinking age from 21 to 18.[7] A few years earlier, while attending Southern Oregon College, he had been co-leader of a student group pushing to place on the ballot a measure asking Oregon voters to make that change.[8]
Klein was reelected in November 1978 to a second two-year term.[9] In January 1979, he was elected House majority whip by his fellow legislators.[10][11]
He ran again for the seat in 1980, but was defeated in the November general election by Republican Rebecca DeBoer.[12]