DETROIT  The General Motors Corporation said on Thursday that about 19,000 factory workers  just over a quarter of its American blue-collar work force  had taken buyouts to leave the automaker.

G.M.’s announcement of the latest job reductions comes as the company is under increasing pressure to cut costs in the face of weak American sales and high gasoline prices.

All of G.M.’s roughly 74,000 U.S. factory workers had been eligible for early retirement packages and buyouts intended to clear the way for hires of lower-wage workers under a deal negotiated last year with the United Auto Workers union.

G.M. said most of the U.A.W. workers taking buyouts and early retirement offers, which ranged up to $140,000 in one-time payouts, would leave by July 1.