Sen. Robert C. Byrd of West Virginia, the longest-serving senator in history, returned to the chamber Thursday for an all-day series of votes on the federal budget.

His appearance surprised many of his colleagues given his series of hospital stays after a fall at his Virginia home last month.

Senators lined up to shake hands or share hugs with the 90-year-old chairman of the Appropriations Committee. Sitting in a wheelchair, the white-maned Democrat appeared happy to chat with his well-wishers and cast votes — loudly enough to be heard in the gallery overhead — on a series of amendments to the federal budget.

As Senate president pro tempore, Byrd is third in line for the presidency behind Vice President Dick Cheney and House Speaker Nancy Pelosi of California, should President Bush ever become unable to serve.

Byrd's presence quieted rumors that had been circulating in recent days about him stepping down from his chairmanship or the Senate. Majority Democrats have been making contingency plans for other senators to take over Byrd's duties when he is absent.