Conversation so far:
What branch of the US armed forces was John McCain part of?
John McCain graduated from the United States Naval Academy in 1958 and received a commission in the United States Navy.
Did being in the Navy make John McCain interested in politics?
Serving as the Navy's liaison to the U.S. Senate represented John McCain's real entry into the world of politics and the beginning of my second career as a public servant.“
Who was John McCain's first wife?
Carol Shepp
What assignment did John McCain have in the Navy?
John McCain was a naval aviator.
Did John McCain serve in active duty?
John McCain's combat duty began when he was 30 years old in mid-1967.

Question: What party did McCain join?
Self-contained rewrite: What party did John McCain join?