Mike Gravel, a former U.S. senator from Alaska who read the Pentagon Papers into the Congressional Record and confronted Barack Obama about nuclear weapons during a later presidential run, has died. He was 91. Gravel, who represented Alaska as a Democrat in the Senate from 1969 to 1981, died Saturday, according to his daughter, Lynne Mosier. In Alaska, he served as a state representative, including a stint as House speaker, in the mid-1960s. He won his first Senate term after defeating incumbent Sen. Ernest Gruening, a former territorial governor, in the 1968 Democratic primary.