Donald J. Trump, whose outsized confidence has been a hallmark of his presidential campaign, implored a crowd of several hundred supporters here on Thursday night not to be complacent in the run-up to Tuesday’s primary. “Don’t think we are going to win,†Mr. Trump, who came in second to Senator Ted Cruz of Texas in the Iowa Caucuses this week, warned the crowd. “No matter where you are, no matter how you feel, I don’t give a d!@#, you got to get out, you got to get out of bed and vote,†Mr. Trump said. It was a seeming change...