In their final days of power, Senate Democrats yesterday granted their longtime Republican ally, New York Sen. Jacob K. Javits, a symbolic final wish. They made him chairman of the Foreign Relations Committee -- for one day.

Javits, the ranking Republican on the committee, lost his chance to become chairman, a post he had long coveted, when he was defeated for reelection. Sen. Charles Percy (Ill.) will become chairman when Republicans take over the Senate in January.

Percy, Sen. Frank Church, the chairman who was also defeated last month, and Sen. Claiborne Pell, now the second-ranking Democrat on the panel, sponsored the resolution honoring Javits. Percy called him "one of the most dedicated, persevering, brilliant minds the Senate has ever known."

The normally verbose Javits, who first came to Washington as a member of the House 32 years ago, said little as he presided over a brief committee meeting. To make a speech, he said, would be "high supererogation at this point."

No minority senator had ever been elected chairman of a committee before, according to Percy. Everett McKinley Dirksen, the late Republican leader, served as chairman of a Judiciary subcommittee at one point. But that wasn't quite the same, because the flamboyant senator was the panel's only member.

Javits has been in the Senate since 1956, and a poll by Ralph Nader's Congress Watch once rated him the brightest senator.