Summer must be over. The well-worn Washington pastime of pampering the press and courting the politicians was revving up last night at one of the first gatherings after the slow season.

It was like the first day of school at Marshall Coyne's cocktail party for NBC State Department correspondents -- and inseparable brothers -- Marvin and Bernard Kalb. They have just written a new novel, "The Last Ambassador," a thinly disguised fictional account based on the U.S.' last ambassador to Vietnam.

The ubiquitous Kalb brothers have been dominating State Department network coverage for the better part of the last decade, first at CBS, then last year both jumped to NBC. They always work together. ("I would have never gone without him," says Marvin. "I like him.")

And everybody seems to like them.

Thirty seconds of prime-time network coverage to a politician here is what going to Africa and coming back with "Roots" meant to Alex Haley.

They live for it. They carefully time their news announcements to coincide with network deadlines. And they turn out in droves when the owner of the Madison Hotel throws a party for two network correspondents who wrote a book, the reviews of which have so far been mediocre.

Still, this kind of socializing is good for business. The network correspondents get their book promoted and politicians possibly get their policies, and themselves, advertised. And although the critics invariably hint that this type of consorting is incestuous, it can make for good parties and reunions.

"Frank!" bellowed U.S. special envoy to the Mideast Philip Habib to Deputy Defense Secretary Frank Carlucci, "I haven't seen you since you introduced me to Lumumba in the Congo in 1962."

Patrice Lumumba was killed mysteriously in the Congo in 1961. But who cares about the year anyway? The important part was that they did meet in the Congo 20 years ago. "I was just a junior State Department official and I showed him around," confirmed Carlucci knowingly.

Presidential counselor Ed Meese stopped by for what is commonly referred to in Washington as "face-time." A handshake, a walk around the room and one drink.

"Didn't I just see you a few minutes ago?" Meese kidded Secretary of Defense Caspar Weinberger. Burst of laughter. Obviously a joke about the constant haggling currently going on over the proposed cuts in the defense budgets.

Weinberger appeared in reasonably good spirits for a department head whose budget is being assailed by the Office of Management and Budget. Asked if he was still talking to OMB Director David Stockman, he grinned. "He and I are fine. He understands the problems we have." Pause. "And we're trying to understand the problems he has."

Surprisingly, most made a gallant attempt to at least skim the book before the party, since it hasn't even hit the streets yet.

"C'mon, Marvin, this guy Tony the CIA operative in the book can't hate the ambassador that much," said presidential adviser Richard Allen.

"And it took me 45 pages to find out this guy Tony's last name. Forty-five pages," complained Allen, flipping through the book to make his point.

"No way," shot back Marvin. He was right. The name appeared on Page 24.

But minor gripes were allowed. Especially if you had read the book. "Congratulations on your first effort. Maybe the next one will be better," teased yet another State Department honcho, Lawrence Eagleburger, assistant secretary for European affairs.

"The Last Ambassador" is in fact the brothers' second shot at collaboration. The first was "Kissinger." And Marvin has written five other books.

Among the guests was one "last ambassador." Tran Kim Phuong was the last Vietnamese ambassador to the United States in 1975. "I started to read the book," he sighed. "But I get so sad every time I read about Vietnam."

And while this ex-ambassador reminisced, some of the other guests worked the room. During the obligatory book-signing, Ed Meese scribbled in one of the books, "With much appreciation to one of my favorite TV inquisitors."

Meese will no doubt be seen from his best side on the NBC evening news sometime soon.