PHOENIX, Ariz. -- Samuel "Joe the Plumber" Wurzelbacher, once a prominent face of John McCain's 2008 presidential campaign, said Sunday that he won't be stumping for the Arizona senator in his close race for reelection. In an interview with FoxNews.com, Wurzelbacher said he was used as a "political tool" during McCain's presidential run and faulted the fourth-term senator for what he described as a weak stance on immigration and border security. "It's supposed to be a closed border. Why don't you uphold the law instead of trying to change it?" he said. "McCain's been a senator for a long time...