As the former Republican congressman, Pete McCloskey represented the state of California for over 15 years. He was the first member of Congress to publicly call for the impeachment of President Nixon after the Watergate scandal and the Saturday Night Massacre. He was also the first lawmaker to call for a repeal of the Gulf of Tonkin Resolution that allowed for the War in Vietnam. In April 2007, McCloskey switched his affiliation to the Democratic Party. 

He is a decorated United States Marine Corps veteran of combat during the Korean War, being awarded the Navy Cross, the Silver Star, and two awards of the Purple Heart. He published a book called Truth and Untruth: Political Deceit in America in 1972. One of McCloskey's enduring legacies is his co-authorship of the 1973 Endangered Species Act.