U.S. presidential hopeful Donald Trump (R) stands with Setya Novanto, Speaker of the House of Representatives of Indonesia, following a press availability after signing a pledge with the Republican National Committee (RNC) at Trump Tower in Manhattan, New York September 3, 2015. Republican front-runner Donald Trump on Thursday bowed to pressure from the party establishment and signed a pledge not to run as an independent candidate in the November 2016 presidential election.  REUTERS/Lucas Jackson