Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Campaign Rally In Louisville, Kentucky
(File/Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Campaign Rally In Louisville, Kentucky
Bernie Sanders (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Campaign Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Campaign Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Campaign Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Campaign Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Campaign Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
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Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders addresses the crowd during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Campaign supporters show their support for Democratic presidential candidate Bernie Sanders as he speaks to them during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Campaign supporters show their support for Democratic presidential candidate Bernie Sanders before a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Campaign supporters show their support for Democratic presidential candidate Bernie Sanders as he speaks to them during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Campaign supporters show their support for Democratic presidential candidate Bernie Sanders before a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Campaign supporters show their support for Democratic presidential candidate Bernie Sanders before a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Campaign supporters show their support for Democratic presidential candidate Bernie Sanders before a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Campaign supporters show their support for Democratic presidential candidate Bernie Sanders before a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Campaign supporters show their support for Democratic presidential candidate Bernie Sanders as he speaks to them during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Campaign supporters show their support for Democratic presidential candidate Bernie Sanders as he speaks to them during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Democratic presidential candidate Bernie Sanders shakes hands with campaign supporters after a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Campaign supporters show their support for Democratic presidential candidate Bernie Sanders as he speaks to them during a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Campaign supporters show their support for Democratic presidential candidate Bernie Sanders before a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Supporters for Democratic presidential candidate Bernie Sanders wait for their candidate to arrive for to a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
Bernie Sanders Holds Election Night Rally In Louisville, Kentucky
Supporters for Democratic presidential candidate Bernie Sanders wait for their candidate to arrive for to a campaign rally at the Big Four Lawn park May 3, 2016 in Louisville, Kentucky. Sanders is preparing for Kentucky's May 17th primary. (Photo by John Sommers II/Getty Images)
