Former Massachusetts governor and 2008 presidential candidate Mitt Romney has announced that he will campaign for Senator John McCain (R - Ariz.) next week. According to McCain's campaign website, Romney will join the senator in Mesa, Arizona for a town hall meeting on Friday, June 4th. McCain, a four-term senator, is leading former Scottsdale Congressman J.D. Hayworth in a close race in the Republican primary in Arizona. The primary will be held in August. The announcement may come as a surprise, as during the 2008 presidential race Romney and McCain, both seeking the Republican nomination, appeared to be bitter rivals.