Anybody can have a ball but not anybody can get the vice president of the United States to attend.

"Al Ullman called me," Walter Mondale told 1,000 ballgoers last night at the first Ambassadors Ball in the history of Washington charity balls.

Al Ullman is Audrey Ullman's husband. Audrey Ullman was ball chairman (a title she liked better than "chairwoman" or "chairperson" despite current feminist usage).

Al Ullman is a Democratic representative from Oregon. He is also chairman (a title he likes, too) of the House Ways and Means Committee.

"Everything" was how Mondale defined the committee's jurisdiction.

"Powerful" was how he described Ullman to the glittering black-tie crowd of foreign ambassadors, Washington officials, corporation executives and volunteers for the National Multiple Sclerosis Society gathered at the Washington Hilton Hotel.

Mondale had no sooner arrived than he started acting like a politician running for public office.

"Just saying hello," he assured reporters who followed him as he worked the crowd.

The next thing he knew he was holding a news conference ("How did I get into this?") while ambassadors and corporation executives seated nearby cocked their ears to listen.

He's have to see what develops, he replied to a question about whether he thinks a Kennedy candidacy might split the Democratic party.

"But I think everybody should have a right to run. I would hope we have a unified party."

Would he consider running with Kennedy?

"I would hope that President Carter will run," he said, "and if he does I will be honored to be his running mate."

"Really," Dick Cavett kidded Mondale, getting even with him for introducing him as Johnny Carson, "I don't think anyone has brought to the vice presidency the qualities that Fritz Mondale has -- since Spiro Agnew."

More than 20 large corporations such as Exxon, Ford Motor Co., General Electric, Occidental Petroleum and Mobil Oil, underwrote the ball. Proceeds were expected to gross around $200,000 and net between $70,000 and $100,000.

It's the most successful Multiple Sclerosis dinner in the history of the city," Mondale announced.

Of the diplomatic corps' 135 envoys, about 60 showed up. Many were there because of the persuasiveness of Anne Apaak, wife of Fernand Spaak, head of the European Economic Community mission in Washington.

"Some didn't understand the importance of the cause," she said. "Some were afraid that by coming they might look frivolous. We are living in a time when nobody wants to look frivolous."

Washington's ambassadorial corps hadn't had so much attention paid it since the Nixon administration. Nixon's first White House party was a white-tie reception for the entire corps. A few years later, then-Secretary of State William P. Rogers entertained the diplomats at another white-tie dinner.

Last night, Soviet Ambassador Anatoliy Dobrynin was in New York and unable to attend in his new capacity as dean of the diplomatic corps. The No. 2 man in rank, the Ivory Coast's Timothee Ahoua, had not yet returned from Africa. It left the ball committee momentarily perplexed until someone thought of perennial favorite OAS Secretary-General Alejandro Orfila.

He shared the dais with the Ullmans, the vice president, Cavett and National MS chairman John McGillicuddy of Hanover Trust in New York.

"Don't call me a substitute," winced Orfila.

In fact, Orfila, along with outgoing chief of protocol Kit Dobelle, became the ball committee's diplomatic advisers.

But it was Roy O. Harris Jr., chairman of the local MS chapter, who first got the idea to throw a party for the city's foreign ambassadors.

An independent public affairs counselor whose friends include the president's son Chip, Harris was befriended by the diplomatic corps a dozen or more years ago when he arrived here from Oklahoma to work in the Department of Agriculture.

"I thought it was time to return the favor," he said yesterday.

He found he had little trouble getting support from Rosalynn Carter, honorary patron (who did not attend), on down the list of official Washington.

Last night, many of the corporate hosts presiding at their $5,000 tables were meeting their diplomatic guests for the first time. For some it held the prospect of future business relations, for others little more than a pleasant evening.

"It doesn't usually help," said International Business Machines public affairs director Les Simons, whose firm was entertaining the Ambassador of Guatemala. "We do business in virtually every country but our business in Guatemala is tiny. We view this as part of our community relations program."

Meanwhile, the 1,000 guests were consuming 125 whole beef tender loins, 10 cases of zucchini, 450 pounds of fresh string beans, 20 flats of mushrooms, 90 gallons of ice cream, 1,000 maraschino cherries ("one for each," said director of catering Paul Limbert) and 25 cases of California wine.

The Chilean ambassador, Jose Miguel Barros, joked that everyone had had gone to a lot of trouble to celebrate his country's national day, which was yesterday.

And Mayor Marion Barry was talking about Washington's future as an international city with its own Office of Protocol. Nobody had ever thought of it before, he said, "because nobody is as visionary as I am."