Any job applicant who failed the drug test would not have been hired, said the official, who insisted on anonymity.

The official denied knowing how many White House employees, if any, may have failed the drug test, or may have acknowledged past drug use in the course of the background checks. "I'm questioning why Mr. Gingrich knows," the official said, adding that, "It's inappropriate for law-enforcement officials to be talking about background checks."

Mr. Gingrich repeated today his previous acknowledgment that, like President Clinton, he had used marijuana many years ago. But Mr. Gingrich, who is 51, said that this was not remarkable for someone who went to graduate school 25 years ago.

"That was a sign we were alive and in graduate school in that era," he said.

An admission of past drug use, even without a positive drug test, can greatly delay an application for a sensitive Government job and can lead to a denial of the security clearances needed for high-level military, intelligence and diplomatic work. More than a year after President Clinton took office, there were reports that some employees had not yet received permanent White House passes because their security applications were still under review, although the delays were not explicitly linked to drug issues.

Mr. Blankley said that last year Mr. Gingrich had joined Representative Frank R. Wolf, a Virginia Republican who serves on a House Appropriations subcommittee that finances the White House, in repeatedly raising the question of links between past drug use and security clearances.