A week ago, Maine Democrat Zak Ringelstein wasn't quite ready to consider himself a member of the Democratic Socialists of America, even if he appreciated the organization's values and endorsement in his bid to become a U.S. senator.
Three days later, he told The Associated Press it was time to join up. He's now the only major-party Senate candidate in the nation to be a dues-paying democratic socialist.
Ringelstein's leap is the latest evidence of a nationwide surge in the strength and popularity of an organization that, until recently, operated on the fringes of the liberal movement's farthest left flank. As Donald Trump's presidency stretches into its second year, democratic socialism has become a significant force in Democratic politics.
Its rise comes as Democrats debate whether moving too far left will turn off voters.