Hart was born in Ottawa, Kan., on Nov. 28, 1936, son of Carl Hartpence and Nina Pritchard Hartpence. The family name later was shortened to Hart.

He went to Bethany Nazarene College, where he met Lee Ludwig, whom he married after graduation. Later he went to Yale Divinity School and Yale Law School.

His first political activism was in John F. Kennedy's 1960 presidential campaign, and after law school, went to Washington where he worked for the Justice Department and Interior Department.

In 1967, he joined a Denver law practice and get involved in Robert F. Kennedy's bid for the presidency the next year. He became campaign manager for South Dakota Sen. George McGovern's 1972 drive for the Democratic nomination.

After McGovern lost the general election to Richard M. Nixon, Hart returned to Denver and in 1974, he upset incumbent Republican Peter Dominick to win a Senate seat. Hart was reelected in 1980.

On Feb. 17, 1983, he began a bid for the 1984 Democratic presidential nomination, finishing a surprising second in the 1984 Iowa caucuses. He stunned front-runner Mondale in the New Hampshire Primary and Maine caucuses, almost knocking Mondale out of the race.

Mondale fought back, questions were raised about Hart's age, name and late naval commission, and Hart's campaign sputtered.

Hart campaigned hard for the party's ticket, which lost in a landslide, and he started working toward another campaign almost as soon as the 1984 general election was over.