DETROIT -- About 6,000 General Motors blue-collar workers have taken the latest round of early retirement and buyout offers, but it fell short of the company's goal, meaning more layoffs are likely, according to The Associated Press.

GM has about 54,000 factory workers and wants to end the year with 40,500, a cut of about 13,500. That means that about 7,500 too few workers took the offers, setting the stage for more layoffs.

The automaker announced in June and July that it would close 15 U.S. factories employing about 22,000 workers by end of 2012.

Spokeswoman Sherrie Childers-Arb said the number of layoffs has yet to be determined because some workers at closed factories could take open jobs at other factories.