The 1972 United States Presidential Election was a realigning election that led to the start of the present 4-party system. In a year when the election was overshadowed by the assassination of the President, the main issue in the election was the Vietnam War. The Democratic Party nominated George McGovern, who ran an anti-war campaign (along with his running mate Mike Gravel who had became famous for his 1-man filibuster to attempt to end the Draft immediately and for publishing the Pentagon Papers) to victory despite alienating blue-collar Democrats. The Republican Party narrowly nominated New York governor Nelson Rockefeller following a very close campaign between Rockefeller and California governor Ronald Reagan.