Former Republican Senate Majority Leader Howard Baker has died, Minority Leader Mitch McConnell announced on the Senate floor on Thursday.
Baker, a longtime senator from Tennessee who also served as chief of staff to President Ronald Reagan from 1987 to 1988, was 88 years old.
In 1973, Baker rose to national prominence as the vice chairman of the Senate Watergate Committee. He famously asked during the proceedings "What did the president know, and when did he know it?"
Later in his career, he was a candidate for the Republican presidential nomination in 1980. He served as the U.S. ambassador to Japan under President George W. Bush.
Baker was known in the Senate as a collegial moderate Republican much loved by leaders of both parties.
He can also credited with saving Ronald Reagan's second term from the Iran-Contra scandal that was crippling the White House. With behind the scenes maneuvering by Nancy Reagan and then-Vice President George H.W. Bush, hot-tempered chief of staff Donald Regan was fired - and the president offered Baker the job.
Baker - who always wanted to run for President again - knew he was forever shutting the door on that aspiration. But he accepted the position and quickly helped Reagan put the scandal behind him.
NBC's Andrea Mitchell contributed.