Baker's death was announced on the Senate floor Thursday by Minority Leader Mitch McConnell, R-Ky., who honored Baker's work as "the Great Conciliator."
"It is with great sadness that I announce the passing of one of the Senate's most towering figures: Senator Howard Baker," McConnell said. "Senator Baker was a true path-breaker... [he] truly earned his nickname: the Great Conciliator."
"I know he will be remembered with fondness by members of both political parties," McConnell said.
Baker was first elected to the Senate in 1967. He came to national attention as the ranking member on the special committee investigating the Watergate affair and the scandal that brought down President Richard Nixon, coining the now frequently used catchphrase, "What did the president know, and when did he know it?"
He became minority leader in 1977 and majority leader in 1980, a job he held, through two aborted presidential runs, until he decided not to seek re-election in 1984. He was chief of staff to President Ronald Reagan during Reagan's second term, helping stabilize a reeling administration in the wake of the Iran-Contra scandal.
He later served four years as ambassador to Japan under President George W. Bush.
"Howard Baker was Tennessee's favorite son, one of America's finest leaders and for Honey and me an indispensable friend," said Sen Lamar Alexander, R-Tenn., in a statement. "He built our state's two-party political system and inspired three generations to try to build a better state and country. It is difficult to express how much we honor his life and how much we will miss him."
"When I think of the ultimate statesman, the very first person who comes to my mind is Howard Baker," said Sen. Bob Corker, R-Tenn. "Howard Baker was one of those people who had the unique ability to bring out the very best in those around him. He always put our country's interests first, and lived a life of service that everyone in public office should aspire to emulate. I have cherished the privilege of being able to sit down and talk with Howard on many occasions, and I will always value his words of encouragement."
Baker is survived by his wife, former Sen. Nancy Landon Kassebaum, R-Kan., and two children from his first marriage to Sen. Joy Dirksen, who died of cancer in 1993.