Weirdly, former Arkansas governor Mike Huckabee sees the biggest gain (even as his base is different than Romney’s), though certainly within the margin of error. But Walker’s big jump is still obvious.
That’s just in Iowa of course. But polling from other shops allows us to make a similar comparison nationally.
Take polling from the Post and ABC News between October and December. Some small jumps for Walker, Sen. Ted Cruz (R-Tex.) and Bush. Walker’s pretty low here, as he’s still more unknown at the national level.