John Sidney McCain III (born August 29, 1936) is an American politician serving as the senior United States Senator from Arizona since 1987. He was the Republican nominee for President of the United States in the 2008 election, which he lost to Barack Obama. McCain graduated from the U.S. Naval Academy in 1958 and followed his father and grandfather--both four-star admirals--into the United States Navy. He became a naval aviator and flew ground-attack aircraft from aircraft carriers.

McCain began his early military career when he was commissioned as an ensign and started two and a half years of training at Pensacola to become a naval aviator. While there, he earned a reputation as a man who partied. He completed flight school in 1960 and became a naval pilot of ground-attack aircraft; he was assigned to A-1 Skyraider squadrons aboard the aircraft carriers USS Intrepid and USS Enterprise in the Caribbean and Mediterranean Seas. McCain began as a sub-par flier who was at times careless and reckless; during the early to mid-1960s, two of his flight missions crashed and a third mission collided with power lines, but he received no major injuries. His aviation skills improved over time, and he was seen as a good pilot, albeit one who tended to "push the envelope" in his flying.  At age 28 on July 3, 1965, McCain married Carol Shepp, who was a model from Philadelphia. McCain adopted her two young children Douglas and Andrew. He and Carol then had a daughter named Sidney.  McCain requested a combat assignment, and was assigned to the aircraft carrier USS Forrestal flying A-4 Skyhawks. His combat duty began when he was 30 years old in mid-1967, when Forrestal was assigned to a bombing campaign, Operation Rolling Thunder, during the Vietnam War. Stationed in the Gulf of Tonkin, McCain and his fellow pilots became frustrated by micromanagement from Washington, and he would later write that "In all candor, we thought our civilian commanders were complete idiots who didn't have the least notion of what it took to win the war."  On July 29, 1967, McCain was a lieutenant commander when he was near the epicenter of the USS Forrestal fire. He escaped from his burning jet and was trying to help another pilot escape when a bomb exploded; McCain was struck in the legs and chest by fragments. The ensuing fire killed 134 sailors and took 24 hours to control. With the Forrestal out of commission, McCain volunteered for assignment with the USS Oriskany, another aircraft carrier employed in Operation Rolling Thunder. Once there, he would be awarded the Navy Commendation Medal and the Bronze Star Medal for missions flown over North Vietnam. Answer this question using a quote from the following article:

What party did McCain join?