"Everyone must be seated before the president gets here," frantically whispered a man beside a camera; he was speaking into a wire around his head.

Outside, February moaned in a city's bones. Downstairs, Jody Powell briefed the Sunday press corps on Camp David. But in the East Room of the White House yesterday, there was only light and magic. The reason was Mikhail Baryshnikov, who had come to dance.

The man who is "perhaps the finest dancer of our lifetime," to quote Jimmy Carter, soared and twirled and magnificently sweated beneath gilt chandeliers and George Washington's portrait on a stage that was roughly one-third the size of what he is accustomed to.

There were maybe 130 people in the room; they seemed to be holding their collective breath each time the Russian raged off his feet. One had the close-up, surreal sense of watching someone skate on a bathtub rink. Or maybe Dwight Stones high-jumping on the set of the "Tonight" show. It was art by compression.

The one-hour concert, which was taped by the Public Broadcasting Service, will be telecast to the nation Easter Sunday night, April 15. It is part of an ongoing series of Sunday afternoon intimate White House concerts that began with Vladimir Horowitz a year ago and continued with Mstislav Rostropovich and Leontyne Price last fall.

The president, who was there in a genuinely delighted smill and blue pinstipes, along with Rosalynn Carter and a demure-looking Amy, said in fact that "one of the many great pleasures of being president" is to be able to present great artists like "Misha" to the American people, especially from the White House. There is always a certain quality to that.

In introducing him before a mike placed in front of the stage, balletomane Carter praised Baryshnikov's courage in seeking to always try new things. The dancer moved last summer from the American Ballet Theatre, where he had danced since 1974, almost from the beginning of his defection, to the New York City Ballet of George Balanchine. "His successes are almost overwhelming," Carter said. His is a talent that transcends national boundaries, that "binds together the human spirit."

Baryshnikov performed four dances -- selections from two famous ballets, "Harlequinade" and "Jewels," an allout 6 1/2-minute rendition of "Tarantella," and achingly sweet waltzes by Chopin, which included a world dance premiere of Waltz Op. 33, No. 2. That one, at three-quarters through the program, brought Jimmy Carter to his feet pounding his applause. Right on cue, up bolted the audience.

What surprises about Baryshnikov is his size: He is small. Compact. Beside him, Jimmy Carter looks like a basketball player. The muscles could have been sculpted by Michelangelo. Nothing about him seems misplaced, even the hair that tousles and mats with each leap. He has a wide, pale, searching sort of face with looks of deep reverie that get broken only by his earthy, almost profane, smiles. The man could be a cinema star -- and was in last year's "Turning Point," for which he received an Oscar nomination.

Baryshnikov was partnered yesterday by Patricia McBride and Heather Watts. Young apprentice dancers from the Washington School of Ballet (they looked to be between 8 and 12) also danced in some of the numbers. It was probably their chance of a lifetime. "Actually, they've all been such pros practicing here this week," whispered Mary Hoyt, Mrs. Carter's press secretary.

Reportedly, the president, hell-bent with affairs of state, nonetheless couldn't resist peeking into the East Room several times during rehearsals this past week.

The guest list yesterday was an amalgam of the nation's art, business, and government institutions. Mayor Marion Barry was there. He had never seen Baryshnikov in person. No, he isn't a balletomane. "I'm learning about a lot of these things." he said modestly. Then he laughed.

Artist Jamie Wyeth said the performance was an extraordinary one -- and he has seen Baryshnikov perform a number of times before. Sen. Thomas Eagleton (D-Mo.) said that, "As a total non-expert, I'd have to say I loved it." He said his wife Barbara, who accompanied him, was the family's resident dance expert.

In the receiving line, Jimmy Carter was asked why this couldn't happen every Sunday. "Hey, that wouldn't be bad," he said right back. Baryshnikov, still dewey with triumph, was standing beside the president. He shook hands with a glazed happiness. In an hour or so he had to go off to prepare for his evening's performance at the Kennedy Center.