White House spokesman Marlin Fitzwater quoted President Harry S Truman yesterday in defense of a high-ranking White House official who came under fire from columnists Rowland Evans and Robert Novak.

In an article yesterday on the op-ed page of The Washington Post, the columnists accused White House deputy chief of staff Kenneth M. Duberstein of seeking to undermine White House chief of staff Howard H. Baker Jr. and force the resignation of Attorney General Edwin Meese III to advance his own ambitions. Fitzwater said the columnists had charged Duberstein with "everything from wife-beating to throwing food in the cafeteria" and that none of it was true.

"As Harry Truman once said, 'If you want a friend in Washington, get a dog,' " Fitzwater told reporters. "Duberstein's at the kennel right now."

Asked later what kind of dog Duberstein was seeking, a White House official said, "One that doesn't bark."Energy Loss . . .

Mary L. Walker, assistant Energy Department secretary for environment, safety and health, has resigned and will leave next month.

Walker took the job two years ago when Secretary John Herrington reorganized the department. Two weeks ago, a National Academy of Sciences report called the department's oversight of its nuclear reactors "largely outside the scrutiny of the public." Walker is preparing a report on improving oversight.No SEA Change? . . .

As the House prepares to vote today on revising the Hatch Act, senior civil servants have weighed in with a word of caution. The Senior From News Services and Staff ReportsExecutives Association said that 67 percent of the members oppose liberalization, while 24 percent favor it.

The SEA, which represents top government managers, surveyed its 2,200 members, and about 20 percent responded in less than two weeks. President Carol A. Bonosaro said these responses probably reflect a consensus.