For the more conspiracy orientated:
Iowa Poll shows big Clinton lead, but also some worriesVermont Sen. Bernie Sanders has replaced fellow populist Elizabeth Warren, a senator from Massachusetts, as the leading contender to Clinton among Iowa Democrats, the poll finds. Sixteen percent of likely Democratic caucusgoers say Sanders would be their first choice for president. That's up from 5% in the January poll.
Now we know why O'Malley really announced, to split the Sanders vote!
Seriously though, it's probably the fact Warren was taken off the list finally, so guessing a good number of likely Warren voters switched to Sanders.
Surprised by the favorability rating of Clinton and Obama though in that poll, would expected lower among democrats, and Sanders a bit higher (though lack of knowledge may attribute to that right now). To tie back to O'Malley looks like he'd have a chance, very early though but could pick up, up to 82%. Very unlikely to happen of course but hopeful is hopeful!