If he does, then he is deluded. Yes, the president energized the left in his campaign, and that was a significant reason for his win in 2008. But he had two other things running in his favor; he wasn't George Bush, and the financial meltdown obliterated John McCain's chances (he was leading, slightly, at the time). In both instances, the net result is that independents moved into the Obama camp, and even people right of center, nominal Republicans, were willing to give him a chance. A hard left turn will make the base happy, but he can't win re-election with a happy base and an alienated center.