The 2012 contest pitting President Obama against a yet-to-be-determined Republican challenger ranks as one of the most intriguing presidential campaigns in history. Two powerful populist factions — the conservative Tea Party movement and Occupy Wall Street protest against income inequality — are helping to shape campaign ideologies and stump speeches. An unusually large field of Republican candidates, including multimillionaire Mormon Mitt Romney and thrice-married Newt Gingrich, have fought each other as aggressively as they have Obama, leaving the GOP so fractured that some think a nominee won't emerge until the party convention in August. Meanwhile, following a controversial Supreme Court ruling on campaign finance, wealthy donors are pouring millions of dollars into TV attack ads through so-called SuperPACs. And overshadowing the entire spectacle is the shaky U.S. economy and the question of which candidate is best equipped to turn it around.