Fighting to recapture the magic of his history-making 2008 campaign, President Barack Obama on Saturday laid out his fullest-yet case for reelection, pleading with struggling Americans to "keep believing in me" and hitting out at presumptive Republican nominee Mitt Romney. "If people ask you what this campaign is about, you tell them 'it's still about hope.' You tell them 'it's still about change,'" he told a cheering mass of supporters at Ohio State University in Columbus, six months and one day before the election.