IA - 2016 Democratic Presidential Primary: Hillary Clinton 55% - Bernie Sanders 26% - Martin O'Malley 4% - (NBC/Marist 07/26/2015) chart & more info

Bernie Sanders
Hillary Clinton
  • Clinton +29

IA - 2016 Democratic Presidential Primary: Hillary Clinton 63% - Bernie Sanders 20% - Martin O'Malley 5% - (KBUR/We Ask America 07/09/2015) chart & more info

Bernie Sanders
Hillary Clinton
  • Clinton +43

IA - 2016 Democratic Presidential Primary: Hillary Clinton 52% - Bernie Sanders 33% - Martin O'Malley 3% - (Quinnipiac 07/02/2015) chart & more info

Bernie Sanders
Hillary Clinton
  • Clinton +19

IA - 2016 Democratic Presidential Primary: Hillary Clinton 50% - Bernie Sanders 24% - Martin O'Malley 2% - (Bloomberg 06/25/2015) chart & more info

Bernie Sanders
Hillary Clinton
  • Clinton +26

IA - 2016 Democratic Presidential Primary: Hillary Clinton 54% - Bernie Sanders 12% - Joe Biden 9% - (Morning Consult 06/15/2015) chart & more info

Bernie Sanders
Hillary Clinton
  • Clinton +42

IA - 2016 Democratic Presidential Primary: Hillary Clinton 59% - Bernie Sanders 15% - Lincoln Chafee 1% - (Gravis Marketing 06/04/2015) chart & more info

Bernie Sanders
Hillary Clinton
  • Clinton +44

IA - 2016 Democratic Presidential Primary: Hillary Clinton 57% - Bernie Sanders 16% - Joe Biden 8% - (Des Moines Register 06/01/2015) chart & more info

Bernie Sanders
Hillary Clinton
  • Clinton +41

IA - 2016 Democratic Presidential Primary: Hillary Clinton 60% - Bernie Sanders 15% - Joe Biden 11% - (Quinnipiac 05/07/2015) chart & more info

Bernie Sanders
Hillary Clinton
  • Clinton +45

IA - 2016 Democratic Presidential Primary: Hillary Clinton 57% - Elizabeth Warren 15% - Joe Biden 6% - (Loras College 04/29/2015) chart & more info

Elizabeth Warren
Hillary Clinton
  • Clinton +42

IA - 2016 Democratic Presidential Primary: Hillary Clinton 62% - Bernie Sanders 14% - Martin O'Malley 6% - (PPP 04/28/2015) chart & more info

Bernie Sanders
Hillary Clinton
  • Clinton +48

IA - 2016 Democratic Presidential Primary: Hillary Clinton 61% - Elizabeth Warren 19% - Joe Biden 7% - (Quinnipiac 02/26/2015) chart & more info

Elizabeth Warren
Hillary Clinton
  • Clinton +42

IA - 2016 Democratic Presidential Primary: Hillary Clinton 68% - Joe Biden 12% - Martin O'Malley 0% - (NBC/Marist 02/15/2015) chart & more info

Joe Biden
Hillary Clinton
  • Clinton +56

IA - 2016 Democratic Presidential Primary: Hillary Clinton 56% - Elizabeth Warren 16% - Joe Biden 9% - (Des Moines Register/Bloomberg 01/31/2015) chart & more info

Elizabeth Warren
Hillary Clinton
  • Clinton +40

IA - 2016 Democratic Presidential Primary: Hillary Clinton 48% - Elizabeth Warren 17% - Joe Biden 13% - (Loras College 01/31/2015) chart & more info

Elizabeth Warren
Hillary Clinton
  • Clinton +31

IA - 2016 Democratic Presidential Primary: Hillary Clinton 53% - Joe Biden 15% - Elizabeth Warren 7% - (CNN/Opinion Research 09/12/2014) chart & more info

Joe Biden
Hillary Clinton
  • Clinton +38