Jon Llewellyn Kyl (/ˈkaɪl/; born April 25, 1942) is the junior United States Senator from Arizona and the Senate Minority Whip, the second-highest position in the Republican Senate leadership. In 2010 he was recognized by Time magazine as one of the 100 most influential people in the world for his persuasive role in the Senate.

The son of U.S. Representative John Henry Kyl, he was born and raised in Nebraska and lived for some time in Iowa. He received his bachelor's degree and law degree from the University of Arizona. He worked in Phoenix, Arizona as a lawyer and lobbyist before winning election to the United States House of Representatives, where he served from 1987 to 1995. He was elected to the U.S. Senate in 1994 and has been re-elected by large margins since.

Kyl was ranked by National Journal in 2007 as the fourth-most conservative U.S. Senator. He has been a fixture of Republican policy leadership posts, chairing the Republican Policy Committee (2003–2007) and the Republican Conference (2007). In December 2007 he became Senate Minority Whip. In February 2011, Kyl announced that he would not seek re-election to the Senate in 2012 and would retire at the end of his third term, which concludes on January 3, 2013. He expressly ruled out running for further office except, if offered, the Vice Presidency.

John Sidney McCain III (born August 29, 1936) is the senior United States Senator from Arizona. He was the Republican presidential nominee in the 2008 United States election.

McCain followed his father and grandfather, both four-star admirals, into the United States Navy, graduating from the U.S. Naval Academy in 1958. He became a naval aviator, flying ground-attack aircraft from aircraft carriers. During the Vietnam War, he was almost killed in the 1967 USS Forrestal fire. In October 1967, while on a bombing mission over Hanoi, he was shot down, seriously injured, and captured by the North Vietnamese. He was a prisoner of war until 1973. McCain experienced episodes of torture, and refused an out-of-sequence early repatriation offer. His war wounds left him with lifelong physical limitations.

He retired from the Navy as a captain in 1981 and moved to Arizona, where he entered politics. Elected to the U.S. House of Representatives in 1982, he served two terms, and was then elected to the U.S. Senate in 1986, winning re-election easily four times, most recently in 2010. While generally adhering to conservative principles, McCain at times has had a media reputation as a "maverick" for his willingness to disagree with his party on certain issues. After being investigated and largely exonerated in a political influence scandal of the 1980s as a member of the Keating Five, he made campaign finance reform one of his signature concerns, which eventually led to the passage of the McCain-Feingold Act in 2002. He is also known for his work towards restoring diplomatic relations with Vietnam in the 1990s, and for his belief that the war in Iraq should be fought to a successful conclusion. McCain has chaired the Senate Commerce Committee, opposed spending that he considered to be pork barrel, and played a key role in alleviating a crisis over judicial nominations.

John Forbes Kerry (born December 11, 1943) is the senior United States Senator from Massachusetts, the 10th most senior United States Senator and chairman of the Senate Foreign Relations Committee. He was the presidential nominee of the Democratic Party in the 2004 presidential election, but lost to then President George W. Bush.

The son of an Army Air Corps serviceman, Kerry was born in Aurora, Colorado. He attended boarding school in Massachusetts and New Hampshire and went on to graduate from Yale University class of 1966, where he majored in political science. He enlisted in the Naval Reserve in 1966 and, during 1968-1969, served a four-month tour of duty in South Vietnam as officer-in-charge (OIC) of a Swift Boat. For that service he was awarded several combat medals that include the Silver Star, Bronze Star, and three Purple Hearts. After returning to the United States, Kerry joined the Vietnam Veterans Against the War in which he served as a nationally recognized spokesperson and as an outspoken opponent of the Vietnam war. During that period, he appeared before the Senate Committee on Foreign Affairs where he deemed United States war policy in Vietnam to be the cause of "war crimes".