Sen. John McCain (R-AZ), a Navy veteran and the ranking Republican on the Senate Armed Services Committee, has been an independent policy voice for many of his twenty-five years in office. McCain served in the Vietnam War, during which he spent five and a half years as a prisoner of war and was subjected to torture. Some forty years later, he led the fight in Congress to ban the use of torture by U.S. troops, even when leaders in his party, including the president, initially opposed such a measure. He also broke with much of his party in backing the 2007 Senate immigration reform bill, which other Republican leaders criticized as essentially granting mass amnesty to illegal immigrants. In 1997, McCain allied with liberal Sen. Russ Feingold (D-WI) to introduce controversial legislation for sweeping campaign finance reform, a version: of which passed in 2001. Since that bill's passage, McCain has faced strong resentment within his own party.
McCain ran against George W. Bush for the Republican nomination in the 2000 elections. In the 2008 presidential campaign, McCain aligned himself with major aspects of the Bush administration's broader foreign policy agenda. McCain opposes any troop withdrawal measures and supports the troop surge in Iraq.
If elected, McCain, 72, would have been the oldest person to win the presidency. He received his party's formal nomination at the September 2008 Republican National Convention in St. Paul, Minnesota. On November 4, 2008, he conceded the race to opponent Barack Obama, who won the presidency by a considerable margin.