(Reuters) - Layoffs of federal workers would be "likely" if too few employees quit under the White House's deferred resignation program, the Washington Post reported on Tuesday, citing a memo from a General Services Administration official.

The government is likely to lay off employees if not enough take an offer to resign now and be paid through September, a GSA official warns. The offer expires Thursday.

More than 20,000 federal employees have informed the U.S. government they are willing to quit their posts under an incentive program that has a Thursday deadline, a U.S. official told Reuters on Tuesday.