AMES, Iowa - Sarah Palin, the former Alaska governor and 2008 vice-presidential nominee who became a Tea Party sensation and a favorite of grass-roots conservatives, endorsed Donald J. Trump in Iowa on Tuesday, providing Mr. Trump with a potentially significant boost just 13 days before the state's caucuses. "Are you ready to make America great again?" Ms. Palin said with Mr. Trump by her side at a rally at Iowa State University. "Are you ready to stump for Trump? I'm here to support the next president of the United States - Donald Trump." Her support is the highest-profile backing...