Washington's Democratic establishment assembled around three television sets at the Averell Harrimans' last night and rapidly watched the town that was theirs become his .

"Looks bad," said one.

"It's not only bad," answered Carter campaign chairman Bob Strauss. "It's real bad."

And from former HEW secretary Joe Califano, assessing the early returns: "If Reagan wins as big as it looks like he's going to win, we'll have to build a phoenix out of the ashes of the Democratic Party."

The Harrimans' elegant old house on a brick sidewalk in Georgetown filled early with the inner-sanctum characters who have become mainstays of past Democratic administrations. Lawyer Clark Clifford, former Arkansas senator William Fulbright, World Bank president Robert McNamara, and Richard Holbrooke drifted from buffet table to television set to Degas sculpture with gloom. There was sadness, and there was anger.

"Carter blew it," said one guest.

From his administration came Al Friendly Jr., press spokesman for Zbigniew Brzezinski; Joe Duffey chairman of the National Endowment for Humanities; and Anne Wexler, senior presidential assistant.

How did she feel, somebody asked her.

"Fine," she said, flat as a day-old Billy Beer.

Strauss himself stayed less than half an hour, running out with a turkey sandwich at 8:30 p.m. His chauffeur carried him away to the Sheraton Washington for what was supposed to be a Carter-Mondale victory party. "You win and you lose," Strauss said on the outside steps of the Harrimans'. "It was damp, and foggy cold. "When you win, you win with style, and when you lose you lose with class."

He turned toward the steps but then looked back and remarked: "What I'm trying to do now is figure out how I can help the new administration."

What the others were trying to figure out about their standing in a new town or even a new administration was hard to judge; saying it out loud would have been like giggling at a wake. And a wake this was, not only for Carter but also for the short span of their lives that touched political privilege and power.

Making things worse were the congressional races that were going to Republicans. Birch Bayh, the Democratic senator from Indiana, went early and so did George McGovern of South Dakota. Others, like Sen. Gary Hart of Colorado, were too close to call.

"There's an awful lot of good people wavering," said George Stevens, AFI founder and co-chairman, drifting between the rooms that also held newscasters Roger Mudd and Marvin Kalb, Joe and Polly Kraft, Henry and Muffie Brandon, J.D. and Carol Williams and editor Clay Felker.

"How are you going to feel tomorrow?" somebody asked George Stevens' wife, Elizabeth.

"Hung over," she sighed.

Next door, at 3042 N St., the moodwas decidedly better. That's because there was a party for Libertarian candidate Ed Clark, who never expected to win. They served pea soup.