PHILADELPHIA — People with lip rings, dreadlocks and tattoos; multitudes of clean-cut types; longhaired men clutching copies of the Marxist magazine Socialist Appeal or the Sartre play “No Exit”; black women intrigued by college-debt relief; gay and transgender supporters; young women in burlappy wear normally seen in Bali; and at least one older guy who said that until recently he had been a Republican.

All stood in line for hours outside the arena at Temple University for a chance to hear Senator Bernie Sanders of Vermont, the 74-year-old self-described socialist who has put up a far more robust challenge to Hillary Clinton for the Democratic nomination than just about anyone expected.

There is a palpable ferocity to their support. They tend to portray themselves less as Democrats fighting for their candidate than as part of a movement of the young and connected fighting to address the gap between the country’s ideals and its realities.

They say they prize authenticity and consistency. In interviews, none expressed a willingness to vote for Mrs. Clinton in the general election if she defeats Mr. Sanders for the nomination.