Democratic presidential candidates join picket lines in Las Vegas before ninth TV debate Democratic presidential candidates including Pete Buttigieg, Joe Biden, Elizabeth Warren and Amy Klobuchar join the picket lines at the Palms Resort and Casino in Las Vegas as members of the Culinary Workers Union fight for a union contract. The presidential candidates are taking part in their ninth TV debate with Michael Bloomberg making is debate debut. Bloomberg and Bernie Sanders and did not join the picket lines. IMAGES AND SOUNDBITES