Yet in just the past few days, the senator from Vermont has angered Florida Democrats with praise for Fidel Castro. He has upset some Jewish leaders with sharp criticism of a pro-Israel group. And his campaign has preemptively spurned billionaire rival Mike Bloomberg’s offer to help fund his campaign in the general election…

Steve Rabinowitz, a longtime Democratic Jewish activist, said he’s puzzled that Sanders picked what he called an unnecessary fight with the American Israel Public Affairs Committee. “It runs so afoul of the politics that I have a really hard time understanding it,” Rabinowitz said. “I know a lot of people who don’t like AIPAC. I don’t know a lot of people who cross the street to curse AIPAC. There is a persuadable middle, and we want them.”

In a recognition of these fractures, Democratic leaders have begun saying openly that some down-ballot party candidates may run on non-Sanders positions if he is the nominee.