Many young voters sat out Super Tuesday, contributing to Bernie Sanders' losses

Young voters cheer Bernie Sanders' anti-establishment message. They turn out in throngs at his rallies. And they form the core of his grassroots efforts to win the Democratic presidential nomination.

But their fiery passion did not translate into the robust turnout he needed on Super Tuesday to win a number of key states, notably in the South where a strong showing by former Vice President Joe Biden has made the nomination contest a two-man race.

Exit polls for five southern states that Biden won – Alabama, North Carolina, South Carolina,...