Sanders, one of two independents in the Senate, is battling the notion that Americans would never elect a president whose ideology includes the word "socialist." Indeed, about three in five Americans say they have a negative view of socialism, according to the Pew Research Center.
The issue came up during last month's Democratic presidential debate, when CNN moderator Anderson Cooper asked Sanders "how can any kind of socialist win a general election in the United States?" While Sanders' numbers are strong among some liberals, he will still have to dispel the view of other Democrats who see him as a candidate from the left-wing fringe, and worry they would be wasting a vote by choosing him over Hillary Clinton in the nomination.