There were two things most people were saying at the Frank Thompson fund-raiser last night.

One was that they didn't think the veteran New Jersey congressman was guilty of anything.

And the other was, "Isn't the view from the roof of the Washington Hotel spectacular?"

These were old-timers, many of them, old-timers from the days when being called a knee-jerk liberal was considered a compliment. There were former Kennedy-Johnson secretary of labor W. Willard Wirtz, former senator Eugene McCarthy, liberal lawyer Joe Rauh.

More than 200 representatives of the various causes Frank Thompson has supported over the years -- the arts, labor, civil rights, education, sports -- crowded the corner of the hotel roof-top that was designated "private party" and admired the view across the White House to the west and down toward the Jefferson Memorial to the south. They reminisced about the old days, clucked over Thompson's current predicament and enjoyed a rather-more-lavish-than-usual fund-raiser buffet -- roast, beef, fresh fruit and veggies, crab cakes and chicken wings for their $150 a head.

Frank Thompson, under indictment on a charge arising from the Abscam investigation, is celebrating his 25th year in Congress. He usually hasn't had a Washington fund-raiser, but his backers thought it might be a good time for a show of support.

The tall (6-foot-3), slim, white-haired House labor subcommittee chairman and -- until the indictment last month, chairman of the House Administration Committee -- greeted guests at the door with a hug here, a warm handclasp there, obviously delighted with the turnout. "It's really wonderful, all these people," he murmured. Evie Thompson, in a pastel Abstract-Impressionist print shirtdress ("I'm head of the New Jersey arts council," she said, "and I liked the pattern") stood next to him, her delight apparent. "We're hanging in there," she said to well-wishers.

Thompson, who was 62 last Saturday, has been accused, along with a companion, of accepting $50,000 in cash during an encounter with undercover FBI agents last fall in a Washington house. He had denied the accusation. f

"I think," said Joe Rauh last night, "of all the people I know, Frank Thompson most deserves the presumption of innocence."

The eclectic mix of Thompson's interests was matched by the mix of guests, from Washington Mayor Marion Barry who swept in, shook "Thompy's" hand (and a few others) and swept out again, to former Supreme Court justice Abe Fortas. From consumer affairs leader Sandra Willett to her arch-opponents, lobbyists Tom Boggs and ex-congressman Jim O'Hara. From old-time lobbyist Donald Dawson to former Redskins star Brig Owens, who was chairman of the affair.

Owens and Thompson met, actually, when the "Over the Hill Gang" co-author rear-ended the congressman in the Baltimore Harbor Tunnel. (Lucky he was in his car, someone said of the still-fit ex-safety.)

"And we've been friends ever since," grinned Owens, who is working for the NFL Players Association and going to law school.

Arts endowment chairman Livingston Biddle was an early arrival and stayed long after many of the 40 or so congressmen and other guests had left for one or another of several similar events last night. Biddle recalled one of the early House floor debates over the arts bill -- Thompson was its original sponsor -- during which arch-conservative congressman H. R. Gross (R-Iowa) moved to include belly dancers in the measure with the intent of ridiculing it to death. During his speech, Gross, referring to humanities, said he wouldn't know one from a bale of hay, recalled Biddle. "Whereupon Thompy said something like 'Here he comes from a farm state and he doesn't know a belly dancer from a bale of hay?' Gross said, well he had a vague idea and Thompy came back with 'I believe he has a vague idea, too,' and that was the last time they tried to laugh that bill off the floor," Biddle recounted, with some relish. "He's a great man," he added of Thomspon. "I believe in him."

"You should do this more frequently," a guest said to Thompson. "There are a lot of people here I haven't seen in a long time."

"Me too," said the congressman.