LAS VEGAS - Democratic presidential candidate Hillary Clinton won unexpected support from chief rival Bernie Sanders on Tuesday for her use of a private email server as US secretary of state, helping to defuse an issue that has overshadowed her campaign.Echoing comments she has made before, Clinton said her decision to not use a government email address was a mistake, but she emphasized that she wanted to focus her energy on policy issues that were more important to voters.Sanders unexpectedly came to her aid. "Let me say something that may not be great politics, but I think the secretary is right," he said. "The American people are sick and tired of hearing about your damn emails."The crowd roared and Clinton beamed."Thank you, Bernie," she said, smiling broadly and shaking hands warmly with the US senator from Vermont amid enthusiastic applause.The moment of warmth contrasted with earlier clashes that the two candidates had over capitalism, gun control and US policy in Syria.Clinton has said her email server in her New York State home was used for convenience and not to skirt transparency laws. The Federal Bureau of Investigation has taken the server and other computer hardware to determine whether sensitive government information was mishandled in Clinton's email correspondence.The issue has hurt Clinton in polls and given fodder to the slate of Republican presidential candidates who would like to be her rival in the November 2016 general election.