Federal agencies could be required to give priority in hiring to former inmates of the District's Lorton Reformatory who complete an experimental educational program while in prison, Sen. Arlen Specter (R-Pa.) suggested yesterday.

Specter, chairman of the Appropriations subcommittee on the District, said at a subcommittee hearing that the priority hiring requirement could be written into the appropriations bills of various government agencies to get the jobs necessary to make the Lorton training program a success.

The senator called the hearing two weeks ago after writing Mayor Marion Barry that he was "frustrated by the lack of concrete progress" in the Lorton program, which has been a pet project of Specter's ever since he succeeded in getting $10 million in federal funding for it two years ago.

After the hearing, Specter said he was encouraged by the report he had received from city officials indicating that the program was progressing. The senator has said he hopes to make the Lorton initiative a model for a nationwide prison education program.

D.C. City Administrator Thomas Downs acknowledged yesterday that the District had difficulties in getting the program started, particularly vocational education, but pointed to some early evidence that increased educational opportunities at Lorton are having an impact.

More inmates are taking the high school graduate equivalency test, and the passing rate rose from 57 to 73 percent in one year, Downs said.

The culinary arts program, which teaches inmates how to cook for hotels and restaurants, has been a particular success, Washington lawyer Richard Ben-Veniste reported at yesterday's hearing. All 60 graduates in the last two years have gotten jobs and none has returned to prison, said Ben-Veniste, a former Watergate prosecutor who has headed an advisory group overseeing the Lorton program.

In a May 24 letter to Barry, Specter noted that the mayor promised more than a year ago to see that more was done to get the Lorton program going.

"Yet we are halfway through another fiscal year, and I continue to receive reports of delays in moving ahead with key portions of the program," Specter said and demanded a detailed report on the program.

Of 3,600 inmates, 1,921 are in education or training programs, officials said. Among the programs are computer repair, floral design, graphics and typewriter repair.

On a related issue, Barry established a 15-member study commission this week to advise him on the type, size and location of a new prison that the city needs to build in the District to relieve overcrowding. The commission, is to make final recommendations in six months.