"Welcome, survivors," Bob Hope told some 2,000 benefit-goers last night at the Kennedy Center as they recovered from two shocks in a very long evening filled with political intrigue and a touch of danger.

The first shock was the arrival of the man who has held everybody on the edge of his political seat the last few days, Sen. Edward M. Kennedy (D-Mass.).

The second was a bomb threat that emptied the Concert Hall for nearly two hours. For Bob Hope, who had ducked a few wartime bombs in his day, last night's bomb threat was the first in a long career.

"No, I've never had a bomb threat, but some of my sponsors have," Hope told his audience when it reassembled at 10:30 p.m. to see the benefit show he staged for the Vietnamese boat people.

The benefit, to which Hope contributed a few minutes of monologue, featured short, funny speeches from Sen. Rudy Boschwitz (R-Minn.) and House Speaker Thomas P. "Tip" O'-Neill (D-Mass.) followed by a preview showing of the comedian's "The Road to China," a television special filmed in the People's Republic of China this summer.

During Boschwitz' turn at the mike, he said, "I've had the pleasure of listening to Bob Hope outside for an hour and not heard him repeat one joke . . . . It's really appropriate that his name would be Hope. He's brought so much hope to us all."

Kennedy's appearance at a prebenefit reception in the Atrium set off a scramble by reporters and guests to get a closer look or a later word. He seemed ready, willing and able, backing into a corner to hold an impromptu mini-press conference.

In the background, music blared competitively so that Kennedy interrupted himself to ask if it could be muzzled or if the 'conference' could move. It couldn't.

Take it right at the top then," Kennedy directed television sound technicians. They did.

"I share the very deep concern about the state of the American economy, continued inflation, growing problems with issues of recession," he began, launching a 10-minute exchange with reporters over his confirmation that he may run for president.

He said that in the past few weeks a number of his House and Senate colleagues had asked him to consider running.

"And I have indicated now that I have not ruled out the possibility of such a candidacy," he said, his face flushed under the lights.

"Well," said Linda Hope, 'Bob's daughter, watching Kennedy go past and listening to the applause in his path. "I've got my candidate already. I'm delighted he's going to run."

"Whenever Teddy's around, there's a lot of hysterics," said O'Neill.

"It was like royalty entering -- which I think he is, political royalty," said socialite Ina Ginsburg.

John McCarthy, who heads the non-profit resettlement organization called Migration and Refugee Services, called Kennedy's presence "fantastic," though not entirely surprising.

"He's on the Senate Judiciary Committee, you know," said McCarthy, "and he's always been positive about our work, a humani- tarian streak which all of us Irish have. We're the original boat people."

Shortly after benefit-goers assembled in the Concert Hall, they realized something was wrong when William T. Hannan, the Washington attorney who pulled the event together, came on stage to advise them of "technical difficulties,"

"Would you all please leave the auditorium by the exits -- I'm very serious," said Hannan.

Waiting backstage to introduce his 2 1/2-hour television special was Hope. He and O'Neill were escorted outside.

A Center spokesman said an anonymous caller had telephoned at 8:20 p.m. to say simply: "Tell Bob Hope -- there's a bomb."

While Hope bantered with the politicans and the audience milling around outside, two dogs trained to sniff out bombs were brought into the Concert Hall by the Army Explosive Ordance Attachment from Fort McNair.

The dogs, along with U.S. Park Police and uniformed Secret Service police, combed the Concert Hall and the areas around it, but found nothing.

Meanwhile, men in tuxedos and women in long dresses strolled past a line of Park Police cars lined up outside the Concert Hall entrance. Some sat chatting on the parked cars. And Hope, O'Neill and ice cream manufacturer Tom Carvel of New York traded jokes.

When someone told Hope that the bomb was going off at 8:45 p.m. (a Center spokesman, however, said the caller had mentioned no time), the comedian deadpanned: "I hope he has the right time, I hope it wasn't coast time."

Nearly two hours later the police let everyone back in, and the show did go on.

After an introduction by Tip O'Neill, Hope told the audience, "That Tip, he carries a lot of weight around Washington. He carries a lot of weight around anyway."

O'Neill was equally complimentary of Hope. Telling how he and Ted Kennedy had encountered one another in the lobby. "We both agreed that Bob Hope is a wonderful guy even if he is a Republican," said the speaker at the reception earlier.

Kennedy never identified the "congressional and Senate colleagues" he said had asked him to consider running for the presidency, but speculation at the party had O'Neill among that group.

Kennedy, asked how long it would take him to make up his mind about running, said he intended to work with the administration on the energy program and economic issues.

"I've set no time frame," he said, "but I've always believed in the primary system. It'll be sometime prior to the primaries to permit the entry in them"

Did he agree with O'Neill that he could have the nomination?

"I think it will be a hard fight, both the nomination and the elections, but this will be the opportunity to discuss both the issues and alternatives to these problems I find people very much concerned about."

Refusing to be drawn into questions about what he and President Carter discussed at their White House lunch on Friday, Kennedy said the real question of the moment was the state of the economy.

"That's going to be decisive next year."

He said he did not think it was a question of Carter's turning the economy around by Thanksgiving as much as one of "taking steps giving people a sense of confidence that it will get better, that people have a return of hope about the future."

As for Miss Lillian's comments to a New Hampshire audience about his health, Kennedy said he saw them "more as an expression of motherly concern than anything else."

After a night of excitement, one woman standing outside the theater commented ruefully to a friend: "When this started, everyone looked so glamorous, and now we all look like we have hangovers."