In his "Nightline" interview Tuesday night, Gary Hart made a statement that conjures up shades of the problem some District residents have with Mayor Marion Barry. "No one's perfect," Hart said, defending the mistakes in judgment that led to his liaison with Donna Rice, "and I wasn't running for sainthood."

The statement struck a familiar chord because Barry, in defense of his rumor-tinged personal life, has often said to friends that he is "a politician, not a preacher."

In both cases, the thinking seems to be that only saints and preachers should be expected to uphold a personal standard of ethics. And while I don't mean to seem puritanical (Hart is right that, as imperfect human beings, we all commit sins), it's partly the schizoid thinking that personal life can be separated from political life in an information society that led to Hart's political demise and continues to hound Barry.

Until recently, while the personal peccadilloes of Barry the man often were thought to be in poor taste, the politician and public servant appeared to be doing a good job.

Despite three years of a federal probe into alleged corruption in District government that focused on the awarding of city contracts, for example, Barry retained the solid support of a majority of city residents, as evidenced by his overwhelming margin of victory in the last mayoral elections.

Therefore, while 11 city officials have been indicted or convicted and another dozen have been dismissed or have resigned under clouds of suspicion, most residents felt the mayor himself was not culpable.

While investigators were looking at city hall, they couldn't help looking at Barry's private life. As a man, he has shortcomings. Rumors alleging cocaine use and womanizing have surfaced repeatedly.

But Barry, the politician, held his own as downtown development boomed, Metro's Green Line to Anacostia finally got under way and the Reeves Municipal Center at 14th and U streets NW began to make a small but noticeable difference in the inner city.

In recent months, however, the alleged excesses of Barry the man are threatening to destroy Barry the politician.

He has made several intemperate statements that defy reason. He outraged many residents when he blamed the horrific performance of the city's 911 emergency ambulance service on poor people jamming the emergency lines while they saved "their big, long cars" to drive to leisure pursuits.

His comment to Jacqueline Williams, the mother of 14 who lived in a city shelter for the homeless and asked for better housing, that she should "stop having all these babies" created such a furor that it catapulted Barry and Williams onto a nationally syndicated television show.

Another example of how Barry the man threatens to destroy Barry the politician was his recent answer to reporters' questions about missing and incomplete financial records from his ceremonial fund that involved the spending of $41,000 from 1984 to 1986.

"I don't think the public elected me to go out and keep hotel receipts," Barry remarked, blaming the problem on inefficient staff members. "Don't talk to me at all. Go find Dwight Cropp {acting secretary of the District} or {press secretary} John White. Don't bug me."

While it is understandable that Barry the man would by now be running on a short fuse, and does not want to take responsibility for the shortcomings of people in his administration, Barry the politician is indeed responsible for the people who keep records of the public's money.

It would be wise to try to reform his government instead of making brusque comments. For while there may have been nothing illegal about the way the funds were spent although the records are missing, at the very least they smack of incompetent management.

Although there are many differences in the public scrutiny of Barry and Hart, Barry has, like Hart, attempted to reconcile his personal and political life on television.

Yet many questions remain. From listening to Gary Hart this week, it seemed he had learned the lesson a bit belatedly about separating the politician and the man. Maybe Marion Barry can take heed before it's too late.