It was the unmistakable voice of Monday Night Football, the soft baritone belonging to Frank Gifford. But on this muggy Sunday afternoon, The Giffer was standing beside the President at the White House, not sitting beside Howard Cosell in a TV booth, and he was describing a flag bearer, not a fullback.

The flag was bl w0062 ----- r e BC-06/14/83-LEVEY 06-14 0001 BOB LEVEY'S WASHINGTON The Day Willie Drew A Smile From A Friend

It was the unmistakable voice of Monday Night Football, the soft baritone belonging to Frank Gifford. But on this muggy Sunday afternoon, The Giffer was standing beside the President at the White House, not sitting beside Howard Cosell in a TV booth, and he was describing a flag bearer, not a fullback.

The flag was blue. It bore the white Special Olympics seal in the center. As a young man carried it up to the reviewing area, Frank Gifford said:

" The flag will be carried today by William James, a Special Olympian from the District of Columbia."

Just as Gifford finished, Willie James passed in front of Ronald and Nancy Reagan. Willie smiled at them, and they smiled at him. "It was," said Willie later, "one of the greatest thrills of my life."

Willie James is the mentally retarded 18-year-old athlete from Northeast Washington whose progress we've been following for several months in this column.

One month from today, Willie and his Washington Capitals floor-hockey team will be in Baton Rouge, La., to compete in the Sixth International Summer Special Olympics. But on Sunday, Willie got a preview of life in front of the TV cameras and the crowds. He was chosen to be the standard bearer for the entire program when Special Olympians put on an exhibition of sports for the President and a gathering of nearly 1,000 people.

Willie had spent much of his big day getting nervous. "I can't explain why," he told me early in the afternoon.

But then he explained why: "I guess it's because I've never met anyone really important before. I've never even been to the White House before."

But by the time the ceremony was over, Willie was beaming.

"He looked just like he looks on TV," said Willie of Reagan. "It was sure different from school, I'll say that. I'd like to do it again. I hope I can."

It's just such confidence that Special Olympics tries to foster.

Many mentally retarded youngsters have been held back for years by their own limitations or inexperience, or kept under wraps by parents and teachers who felt that mentally retarded children were incapable of coping with visibility and pressure.

But when one of their number carries a flag within three yards of the President of the United States and exchanges smiles with him, the message is clear:

If a retarded child can do that, perhaps he can express himself easily and clearly to a stranger, or learn to shop in a grocery store, or get and keep a job. As Willie James himself said after carrying the flag past the President, "I don't know what I was nervous about. It wasn't that difficult. Right now, I feel like I could do anything."

Twelve years ago, there were a lot of things that Willie James couldn't do.

"He was a very hard one to figure out at first," said Sister Mary Dolores Wilson, the principal of Kennedy Institute in Northeast, a school for the mentally handicapped that Willie has attended since he was six.

"We couldn't figure out what was wrong with him. He wouldn't tell us what was wrong with him. Sometimes he would burst into tears for no apparent reason. He had a lot of trouble communicating."

But Willie has "made a great deal of progress," Sister Dolores said. He can now handle situations and people he hasn't encountered before, and his classwork is "improving steadily."

Willie isn't ready to graduate yet. Because of his mental handicap, the cause of which remains uncertain, he can still barely read or add a column of figures. He is likely to remain at Kennedy until the legal age limit of 21.

But the school's administration just cast a vote of confidence in favor of Ronald Reagan's friend. They hired Willie James to be the school's summer custodian at $3.35 an hour. It will be the first full-time paying job Willie has ever had.

"If I can do this job, then maybe I can do another when I get older," said Willie. "It'll be nice to have the money, anyway. And it'll be nice to have it in Louisiana. I just wish it was tomorrow. I can't wait."