Sen. Bernie Sanders endorsed Florida Democratic Senate nominee Angie Nixon on Thursday, two days after she stunned the party establishment by defeating heavily funded favorite Alex Vindman.Why it matters: Sanders gives Nixon a prominent national progressive ally as she pivots to a difficult general-election race against Republican Sen. Ashley Moody.Sanders also cast Nixon as a model for the Democratic Party's future.What he's saying: "Angie is proof that organized people can take on the organized money of the wealthy and powerful — and win," Sanders said in a statement released by Nixon's campaign.Sanders praised Nixon's support for Medicare for All, canceling medical debt, expanded child care and paid family leave.The intrigue: Nixon won the primary without Sanders' endorsement despite working on his 2016 presidential campaign and running on many of the economic policies he made central to his campaigns.The big picture: The endorsement strengthens Nixon's connection to the national left, but it also gives Republicans another opening to make socialism the centerpiece of the fall campaign.Reality check: Nixon still faces a steep climb against Moody in Florida, a state that has shifted sharply to the right and where Republicans have dominated recent statewide elections.Editor's note: This is a breaking news story and will be updated.