Five Democratic presidential candidates will square off tonight in Las Vegas for the first of six debates in the 2016 campaign. The participants are former Secretary of State Hillary Clinton, Vermont Senator Bernie Sanders, former Maryland Governor Martin O’Malley, former Virginia Senator Jim Webb and former Rhode Island Governor Lincoln Chafee. Hawaii Congressmember and Democratic National Committee Vice Chair Tulsi Gabbard will not be attending today’s debate. She says she was disinvited after publicly calling for more than six debates. We’ll bring you a preview of tonight’s debate after headlines.