A man who spent 20 years trying to leave Cuba unwittingly deported himself and his family from the United States for what he thought would be a 20-minute excursion to the Canadian side of Niagara Falls.

Three weeks after they left their Miami home on the trip, Carlos Fajardo, his wife and two adopted children remain stranded at a motel in Canada.They set out Dec. 20 on a Christmas quest for snow, which his adopted children, Yoandys, 12, and Yordalys, 9, had never seen.

Even though the family lived in the United States for four years, immigration officials will not allow them back because they are illegal aliens.

"We came for 20 minutes," Fajardo said. "No one told us we could not go back."

Sen. Bob Graham, D-Fla., has joined the Fajardos' cause by asking officials to let the family back.

"This family has strong ties to the Miami community through relatives, business and local school attendance," Graham said in a letter to Immigration and Naturalization Service officials. "It would be comforting to these people for them to be able to resume their well-established lives."

Fajardo, 39, a small, soft-spoken man who tried for two decades to leave his native Cuba, said the family drove 1,500 miles in their truck to Niagara Falls, N.Y., where they checked into a motel and planned to visit Canada.

He told Canadian border guards his family wanted to see the Horseshoe Falls.

When the family returned, however, U.S. border guards demanded proof of their citizenship. All Fajardo had was a Florida driver's license.

At first, Fajardo maintained he was a U.S. citizen. Later, he said he was a resident alien. But immigration officials, after a search of their records, determined otherwise.

Benedict Ferro, director of the INS office in Buffalo, said Fajardo's wife, Bermaida, and her two children entered the United States illegally in 1985 and Fajardo entered the country illegally in 1986.

Fajardo denies entering the country illegally.

An immigration judge in 1987 denied asylum to Mrs. Fajardo and the two children. She appealed the decision in August on grounds that she would face persecution if returned to communist Cuba, but her appeal was rejected.

Fajardo's application for asylum was pending when he crossed the border.