The Democrats dressed up for their humongous annual fundraiser at the Washington Hilton last night, and since it's less than 300 days to the convention and just a shade over 13 months to the election, the place turned into one gigantic campaign stop.

Every Democratic presidential candidate came, except for Reubin Askew and Fritz Hollings. The emcee was the Democratic Party chief--introduced during a booster film as "Your Chairman, Charles T. Manatt," a man who "time and time again has willingly and unselfishly given up personal and business opportunities for his country and his party."

It was that kind of evening.

It was difficult to tell, but it looked like Sen. John Glenn of Ohio got the most attention at the pre-dinner cocktail reception. It was certainly easy to get elbowed in his wake.

"Great turnout tonight," said Glenn, who was chatty. But then, his better looking younger brother, as some have called actor Ed Harris who is playing him in the movie "The Right Stuff," is on the cover of the current Newsweek, which can't be all bad.

"I don't know anything about it, of course," said Glenn of the movie that features him bravely humming "The Battle Hymn of the Republic" as he faces possible incineration upon reentry into the Earth's atmosphere. (The possible incineration is true, but the humming is a figment of Hollywood.) "But we're glad something's coming out about that time period."

Will it help his campaign for the presidency?

"Oh, I have no idea," he said.

He has, however, read the book by Tom Wolfe and "was happy with the way the whole thing came out." He also said that yesterday he returned the call of Harris, but got a busy signal.

"I'm looking forward to meeting him," he said.

Meanwhile, Mondale had arrived. He's looking forward to the expected AFL-CIO endorsement. But what did he think about Democratic Party officials who reportedly say their hearts are with him, but they think only Glenn can beat Reagan?

"Richard Wirthlin Reagan's pollster has said both publicly and privately that I'm the strongest candidate--and I agree." He smiled. "That's your lead."

By 8 p.m., more than 1,700 people crowded into the Hilton ballroom. At $1,000 a plate, they ate filet mignon with hollandaise ("Can you imagine 1,700 microwaved pieces of meat?" said one party official. "Boggles the mind.") Former president Jimmy Carter had planned to make the remarks after dinner, but because of the funeral of his sister, Ruth Stapleton, Rep. Morris K. Udall of Arizona took his place.

"The Democratic Party, in all its years in power," Udall said, "never lost the America's Cup."

The evening was expected to raise $1.6 million for the Democratic National Committee. It was also an excellent place to let everyone see that you're still around. Candidates' staffers took down the right names, a lot of the people who skulked away after the defeat in 1980 were suddenly back, and as usual, the whole evening was 45 minutes behind schedule.

The gala was one of George McGovern's first evenings out with his competitors. Asked what kind of movie he'd like to be made about him, he replied: "I'd like to rerun my acceptance address of '72 because nobody saw it. It came on at three in the morning and everyone except my mother was asleep. But we did well in Guam, where it was prime time."

Milling around in the crowd was Sen. Alan Cranston, who is trailing front-runners Glenn and Mondale. Here is what he said about McGovern:

"A man who was zero in the polls in '72, who nonetheless won the nomination, and then lost to Richard Nixon, who proceeded to be forced out of office, can't help but think he can do it again."

Sen. Edward Kennedy of Massachusetts, who's not running, nonetheless got a lot of attention. "Oh, please, can I have your autograph for my Joshua?" asked one woman.

Jesse Jackson, who still hasn't decided whether he'll run for president, had plenty to say. "We're sowing the seeds for a new course," he said. "And we're allowing the time for those seeds to germinate."

"Oh, please, could you sign this for my Joshua?" asked the same woman.

Among others at the party was Robert Strauss, the former party chairman, who had just come from Richard Nixon's testimony before the Kissinger Commission on Central America. "He was splendid," said Strauss. "Whether one agreed with him or not, he gave a great lesson in history."

At this point, McGovern wandered up. "How's my campaign manager?" he asked Strauss. ("Just a joke," McGovern said later.)

Strauss laughed. "He's a very close personal friend of mine," he said of McGovern. "I just sent him a check."