MARSHALLTOWN, IA -  JANUARY 15: Former U.S. President Bill Clinton greets guests after speaking at a campaign event for his wife,  Democratic presidential candidate and former U.S. Secretary of State Hillary Clinton, at Marshalltown Community College on January 15, 2016 in Marshalltown, Iowa. Both Republican and Democratic presidential candidates and their surrogates have been making appearances at events across Iowa to build support in advance of the 2016 Iowa Caucuses.  (Photo by Charles Ledford/Getty Images)