History repeats itself, until it doesn't. That musty saw is worth remembering as pundits speculate on whether the lumbering economy will doom the re-election hopes of President Obama, who has shown a knack for beating odds and breaking barriers.

If high unemployment "was a killer, he'd already be dead," said Republican pollster and consultant Mike McKenna. "The survey data tells you he's not dead." Yet Obama runs even with, or slightly ahead of, Republican rival Mitt Romney in poll after poll.