Mike Gravel, former Democratic U.S. senator from Alaska and two-time presidential candidate who read the Pentagon Papers into the Congressional Record, has died at the age of 91. Gravel ran for the 2008 Democratic presidential nomination as a vocal critic of the U.S. invasion of Iraq. During a 2007 presidential debate, Gravel confronted then-candidate Barack Obama about using nuclear weapons. He switched from running as a Democratic candidate to a Libertarian one after opposing the military-industrial complex and imperialism that permeates the Democratic Party. Later in the show, we’ll air excerpts of Mike Gravel reading the Pentagon Papers in 1971 and speaking in 2007 about the events leading up to the historic reading.