[...] it's the nation's first primary and the next in a series of clues into what Americans want in their next president. Republican hopeful Marco Rubio is downplaying his rough outing in Saturday night's GOP debate, while touting his overall campaign momentum after his third-place finish in the Iowa caucuses, hoping to use that momentum to boost his chances in Tuesday's contest. Donald Trump, who finished second in Iowa, is pleased with his debate performance and place atop New Hampshire's GOP polls, and he's doubling down Sunday on his call for the U.S.