Landra Reid, Reid's wife of 62-years, released a statement saying that Reid, a former amateur fighter who represented Nevada in Congress as a Democrat over three decades, had lost his battle with pancreatic carcinoma.
Landra Reid stated, "We are so proud about the legacy he left behind both on national stage and in his beloved Nevada."
Reid was the majority leader and served as President Barack Obama’s point man in Senate. He helped to pass Obamacare in Congress in 2010, despite fierce Republican opposition.
Obama posted Tuesday to social media a letter he wrote to Reid.
Obama wrote the letter, "You were a great leader at the Senate, and you were more generous than I could have expected,"
"I would not have been elected president if it wasn't for your encouragement, support, and most importantly, I wouldn't be able to get the majority of what I did without your skillful and determined determination."
After the Democrats gained control of the Senate in 2007, he had been promoted to the position of majority leader.
Although Reid was a moderate political figure who disagreed with others in his party on abortion and the environment and gun control, he clashed frequently with Republicans and maintained poor relationships with congressional leaders of the opposition party.
Reid stated in 2004 that he would prefer to dance than fight, but that he knew how to fight. This was a reference to his boxing career.
2012: Senator Mitch McConnell was the top Republican in the Senate. Reid, however, accused McConnell for a breach on an important issue.
Major legislation was stalled during Reid's tenure as majority leader because Republicans and Democrats couldn't reach compromises.
McConnell's relationship was so fraught that Reid shunned Reid during critical US fiscal policy talks, and instead dealt directly with Vice President Joe Biden.
Reid was fed up with Republican procedural blocks blocking Obama's nominees for the judicial and executive branches. He pushed through the Senate an historic amendment to the Senate's filibuster rules. This prevents any minority party from blocking presidential nominations except for those to the Supreme Court.
Reid said to his fellow senators that there had been "unbelievable, unprecedented obstruction", referring specifically to Republicans. "The Senate can survive and it must evolve as it has throughout the history of this great nation."
Republicans claimed that the move was a pure power grab.
Reid was elected first to the House in 1982. He was then sent to the Senate in 1986 by Nevada voters.
He displayed remarkable resilience in overcoming spirited re-election challenges.
Reid retired in 2016 after suffering broken ribs, facial bones, and an eye injury while exercising at home.
Reid and Landra had five children.