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Trump replaces Walker as Iowa frontrunner

Scott Walker is fading so fast in what was his strongest state, it's almost as if he'd been hit with a scandal or humiliating revelations.

Florida Senator Marco Rubio, retired neurosurgeon Ben Carson, Wisconsin Gov. Scott Walker, and real estate magnate Donald Trump return to the stage following a break in the Republican presidential primary debate on August 6, 2015 at the Quicken Loans Aren
Florida Senator Marco Rubio, retired neurosurgeon Ben Carson, Wisconsin Gov. Scott Walker, and real estate magnate Donald Trump return to the stage following a break in the Republican presidential primary debate on August 6, 2015 at the Quicken Loans Arena in Cleveland, Ohio.AFP – Getty Images

Steve Benen is a producer for "The Rachel Maddow Show," the editor of MaddowBlog and an MS NOW political contributor. He's also the bestselling author of "Ministry of Truth: Democracy, Reality, and the Republicans' War on the Recent Past."