Trump: Obama should be investigated over Clinton email server

By Steve Holland and Emily Stephenson DORAL, Fla./WASHINGTON (Reuters) - U.S. Republican presidential candidate Donald Trump said on Tuesday that President Barack Obama must be investigated over a private email server Hillary Clinton used while secretary of state, saying Obama "knew all about" her email arrangements. "That's why he stuck up for Hillary, because he didn't want to be dragged in. Because he knew all about her private server," Trump said of the Democratic president in an interview w