Sen. Ted Cruz attends campaign event in Boone, Iowa

Sen. Ted Cruz (R-TX), 2016 Republican presidential candidate, walks in the snow as he steps off his "Cruzin' to Caucus" bus as he arrives to campaign at the King's Christian Bookshop, January 4, 2016, in Boone, Iowa. Cruz is running against a large field of GOP candidates, including real estate mogul Donald Trump, former Sen. Marco Rubio and retired neurosurgeon Ben Carson, Iowa's first-in-the-nation caucuses are February 1. Photo by Mike Theiler/UPI