If Hillary Clinton pulls off a victory in her close race for the Democratic presidential nomination with Bernie Sanders, she will have women like Joan Pinnell to thank.

Pinnell, a 32-year-old Chicagoan and former volunteer for Barack Obama's 2008 campaign, has been knocking on doors in Iowa in support of Clinton, Obama's former rival for the Democratic nomination.

Her dedication stems in part from the desire for a president who can "personally understand the struggle that it is to be female" — a factor that was far less important to her back in 2008 when she was in her mid-20s.