Self-described "democratic socialist" Bernie Sanders says he can win a general election by exciting young people, the middle class and working-class people and driving up voter turnout.
The Vermont senator says in Thursday's presidential debate that the rise in turnout will help Democrats keep the White House, gain seats in Congress and win governors' races.
Sanders says, "Democrats win when there is a large voter turnout, when people are excited."
He says Republicans win office when voters are "demoralized" and turnout is low.
Hillary Clinton argues that she is the strongest candidate to take on the Republicans, and she hopes to persuade young people currently backing Sanders to come over to her side.