WEST BURLINGTON, Iowa - Bernie Sanders doesn't kiss babies. He promises them a revolution.

During a recent campaign stop in Iowa, the Democratic presidential candidate told 3-month-old Lily Landretti that he was doing this for her. By this, he meant his populist campaign.

In an age of carefully planned campaigns, the Vermont senator is different. A self-identified grump, Sanders gets angry, rolls up his sleeves and winds up drenched in sweat.

Like Donald Trump in the Republican race, Sanders has been drawing big crowds and giving the buttoned-up candidates a run for their money.

For supporters, Sanders' grouchy persona is one of his charms. They say he feels like a real person. They like his liberal message and his pledges to work for single-payer health care, paid maternity leave and a higher minimum wage.