His national stature grew throughout his governorship. In 1972, he delivered the keynote address at the Democratic National Convention in Miami Beach. The nominee, Senator George S. McGovern, discussed the vice presidency with him, but he was reticent. He was elected chairman of the Southern Governors’ Conference in 1974 and of the Democratic Governors’ Conference in 1976. In 1979, President Carter named him the United States trade representative, with cabinet and ambassador’s rank, a post he held for two years.

In 1981, he began exploring a run for the Democratic presidential nomination. He visited all 50 states and announced his candidacy in 1983, billing himself as “a different Democrat.” A Harvard study called him one of the century’s 10 best state leaders, along with Woodrow Wilson and Theodore Roosevelt.

But his campaign never gained traction. While progressive on civil rights, he was more conservative in some ways than his rivals — among them former Vice President Walter F. Mondale, Senator Gary Hart of Colorado and the Rev. Jesse Jackson — favoring the death penalty and generally opposing abortion and civil rights for gay people. In March 1984, he dropped out after finishing last in the New Hampshire primary (won by Mr. Hart).

In 1988, lacking funds, he halted a brief run for the United States Senate, ending his political career. He later taught government and politics at Florida International University, Florida Atlantic University, Florida A&M University, the University of Florida and Florida State University, which named its school of public administration and policy after him. The University of Florida named its institute of politics and society after him.

Reubin O’Donovan Askew was born on Sept. 11, 1928, in Muskogee, Okla., the youngest of six children of Leon and Alberta Askew. His father, a carpenter, was an alcoholic, and his mother divorced him and moved the brood to her hometown, Pensacola, Fla., in 1937. She was a waitress, seamstress and hotel maid, and Reubin shined shoes, bagged groceries and delivered newspapers to help support the family. He attended Christian Science services with his mother before later becoming a Presbyterian.

He graduated from Pensacola High School in 1946, served two years in the Army and, through the G.I. Bill, attended Florida State in Tallahassee, where he was student body president. He joined the Reserve Officers’ Training Corps and, after earning a degree in public administration in 1951, became an Air Force officer during the Korean War. In 1956 he graduated from the University of Florida law school, in Gainesville, and joined a Pensacola law firm.