BURLINGTON, VT - MAY 26:  Democratic presidential candidate U.S. Sen. Bernie Sanders (I-VT) delivers remarks while officially announcing his candidacy for the U.S. presidency during an event at Waterfront Park May 26, 2015 in Burlington, Vermont. Sanders will run as a Democrat in the presidential election and is former Secretary of State Hillary ClintonÕs first challenger for the Democratic nomination.  (Photo by Win McNamee/Getty Images)