The cream of Washington's local Democratic Party gathered at the Washington Hilton last Friday for the semi-annual Kennedys-King dinner--just about everyone, that is, except Mayor Marion Barry.

While party Chairman Theodis R. (Ted) Gay cheerfully greeted the nearly 400 guests--including all but one member of the City Council--Barry was in Atlantic City watching the Michael Spinks-Dwight Braxton light heavyweight championship fight.

Barry said his last-minute decision to skip the dinner and zip off to the gambling capital of the East Coast was simply a matter of priorities: He's a hard-working man who puts in 14- to 16-hour days, and he's entitled to take a little time off to relax and pursue his interests.

"I've got news for all of you who don't like me to go to a fight--I'm not going to work 14 hours a day and not go to a fight, or to a basketball game or to take my son swimming," the mayor told a gathering of the Washington Press Club upon returning from his weekend trip.

Barry said he doesn't know why anyone would be upset by his decision to travel to Atlantic City, rather than attending a staid Democratic dinner in Washington. Besides, the mayor said, he made sure he was well represented at the dinner by aides and political supporters. Certainly, he meant no disrespect to the party, Barry added.

"If I'm going to snub, I know how to snub," he said.

But, in fact, the mayor's conspicuous absence from the $125-a-ticket dinner--the local party's biggest event of the year--was viewed by some as a deliberate snub of Gay, whose relationship with Barry has been, at best, a cool one.

Barry and his campaign aides were angered last fall when Gay discouraged members of the D.C. Democratic State Committee from endorsing the mayor until after his Sept. 14 primary battle with Patricia Roberts Harris and several other challengers.

After his reelection last November, Barry privately boasted that he would oust Gay and take control of the local party, but his quiet efforts appear to be failing. Gay, a friendly, low-key political technician who is active in national Democratic Party affairs, enjoys widespread support within the party and now appears certain of winning a second term as party chairman in June.

Barry denies that he personally tried to oust Gay, and says their differences have been exaggerated.

"Barry and his people are frustrated that they can't defeat Ted without being heavy-handed," said one high-ranking party official who attended last Friday's dinner. "Unless they can make the party their own, they never wanted to get involved."

Gay reportedly was upset by Barry's refusal to attend the dinner. Nonetheless, he seemed placid and highly diplomatic Friday night as he mingled with his guests, including Council Chairman David A. Clarke and the wives of Democratic presidential candidates Walter F. Mondale and Sen. Gary Hart of Colorado.

Pressed to explain why the mayor wasn't at the dinner, Gay responded: "The mayor has a very nice letter in the dinner program. . . . I know what our working relationship has been over the last months. I think this is a great event. Ah, I don't know what else to say."

The usually contentious relationship between the government and the press has long been a matter of intense interest and debate in Washington--and the subject of numerous treatises.

Now comes D.C. Budget Director Elizabeth C. (Betsy) Reveal, co-author with Gordon Chase of a new book entitled "How to Manage in the Public Sector," to advise bureaucrats on how to deal with obstreperous reporters.

Reveal warns her public-sector colleagues that journalists are more concerned with getting a scoop or exposing a scandal than casting light on the day-to-day operations of government.

"They reporters are seldom there when you want them and ever-present when you do not," she wrote. "They are always accurate and precise when it is unimportant, and superficial and misleading when it is not. There is always a world crisis dominating the news on days when you have good stories to report, and little happening when you are caught with your pants down."

She advises government officials to get to know reporters better; organize their press operations carefully; keep churning out positive press releases, even if they're ignored at first; and try to anticipate bad news and beat the news media to the punch whenever possible.

But in the end, Reveal acknowledged, government agencies have to peform well before they can expect to see complimentary stories in the press. And above all else, she added, tell the truth.

"If anyone in your entire working world is likely to catch you in a lie, an evasion, or a 'mistruth,' it is the press," she said.