Former Vice President Joe Biden speaks at the International Association of Fire Fighters legislative conference in March. He got into the Democratic presidential nomination fight Thursday.
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Sen. Bernie Sanders speaks during a campaign rally in June 2016 at Qualcomm Stadium in San Diego, Calif. He launched a second presidential campaign on Tuesday, with a big burst of donations from supporters, but new challenges ahead.
Sen. Kamala Harris, D-Calif., at an Oakland, Calif., campaign rally this week. Harris says she backs a single-payer health system, but she hasn't yet offered details on how she would finance that plan.
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Sen. Bernie Sanders, I-Vt., leads a November 2015 rally in front of the New Hampshire State House in Concord. Sanders won that primary, but today some of his supporters in the early primary state are less enthusiastic about another presidential bid.
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Puerto Rican Nerybelle Perez poses with a portrait of her father, World War II veteran Efrain Perez, who died after his ambulance was turned away from the island's largest public hospital when it had no electricity or water following Hurricane Maria.