No Republican presidential hopeful this year has more riding on Iowa than Wisconsin Gov. Scott Walker.
After leading in polls in Iowa most of the year, Walker is suddenly slumping. And he might have Donald Trump to blame.
It's not necessarily that the support Walker had earlier in the summer, when he was the clear front-runner in Iowa polls, has gone to the real estate mogul. Ben Carson, Carly Fiorina and Ted Cruz have seen something of a surge since the first presidential debate.