In theory, reporters should not become chummy with public officials.

When the subject of a critical news story is your friend, it is hard to be impartial.

Journalists who cover government officials try to avoid compromising their impartiality. They prefer an adversary relationship. On saturday night, President Carter noted approvingly that the Founding Fathers wanted it that way.

The president spoke at the annual White House Correspondent's Association dinner-or perhaps "performed" would be a more appropriate word. His speech was witty and his timing was worthy of a Jack Benny.

More important, there was a message in his gentle humor. The message was: It is in the nature of things that you and I must frequently be at odds. But I respect you for doing your job, even though you sometimes give me a big, fat pain in the neck, and I hope you respect me for doing my job.

When it was all over, newsmen asked their colleagues, "How do you think he did?" The answer, very frequently, was, "I think he made a lot of friends." Or, "Real good. This will help him." How strange it was to hear these words from men and women who pride themselves on not permitting their personal likes and dislikes to influence their reporting.

I am not the best of witnesses on this matter because my own tenure at covering the White House was short (Roosevelt and Truman) and attitudes were somewhat different then.

Nevertheless, I do have an opinion, and it is this: However hard newsmen work at being impartial, their personal preferences, beliefs and friendships do creep into news reports.

Franklin D. Roosevelt generated intense reaction. Either reporters liked him a lot or they disliked him with similar fervor, and their feelings were sometimes evident in their writing.

Truman, who came to Washington with the support of a corrupt political machine, ended his career with an excellent press. Many reporters admired Truman's earthiness and common sense, and they appreciated his accessibility (except, perhaps, when he sat in on their poker games and outplayed them).

That kind of camaraderie never hurts a public official, and sometimes it helps.

The Eisenhower years brought abrupt changes in tone, style, procedure and relationships. The news stories and commentaries of those eight years reflected the changes.

The pendulum swung sharply agiain when Kennedy took office. His elan and verve set a new tone, and press reaction was akin to that of FDR's day. People tended to be very much for Kennedy or very much against. It was difficult to maintain a posture of professional impartiality.

Lyndon Johnson was a complex man, judged differently by different people or by the same people at different times. It is too early to know that will be left when history finishes its distillation of the news stories of the Johnson years.

The press coverage of Richard Nixon's tenure is a good example of how difficult it is for human beings to stifle their biases. Even before Watergate, there was no love between Nixon and the press. After the story behind the break-in began to unravel, people all over the world could sense how it would have to end.

In teory, Nixonhs misdeeds were reported by deadpan, dispassionate journalistic automations. In fact, neither the man nor his deeds lent themselves to disinterested reporting. Nixon made political alliances, but few friendships.

Jerry Ford the man was a lot easier to like than Jerry Ford the politican, and that did him no harm.

On Saturday nigh, Jimmy Carter the man kidded Jimmy Carter the politician. There is reason to think that Carter, like Ford, will benefit from his warmth as a human being. But as Reggie Jackson can explain to both men, being cheered or booed when you come to bat isn't nearly as important as the ability to hit home runs at crucial moments.

Theoretically, we reporters sit on Olympus and judge ordinary mortals with impartial objectivity. But just between you and me, I don't know any reporters whose minds and hearts are constructed of electrical wiring and programmed computers. The people I know are made of flesh and blood and conscience. They have ideals and thoughts and beliefs that sometimes interfere with complete impartiality-not because the reporters want to have these attributes but because God made them that way. That can't be all bad, can it?