Warren and many on her campaign responded intensely after POLITICO reported that the Sanders campaign had quietly deployed talking points to its canvassers in multiple early states that included language attacking her electability.

The talking points weren’t particularly vicious, but the leaked script struck a raw nerve with Warren and her campaign because they felt they had held up their end of a nonaggression pact with Sanders — even after some Sanders staffers and surrogates had spent most of the race hitting Warren. The Warren campaign got so frustrated about critical tweets and comments from Sanders’ staffers that it privately expressed its displeasure to Sanders campaign manager Faiz Shakir last summer.

But top Sanders aides kept throwing elbows throughout the fall. “There are people who didn’t have the same guts and the same courage as Sen. Bernie Sanders to run in 2016. There are some people who sat on the sidelines when it was hard,” Turner, Sanders’ campaign co-chair, said late last year, one of many jabs — some veiled, some not — that Warren allies stewed over, frustrated that Warren world wasn’t hitting back. “There was only one person who stood up to the establishment and his name is Bernard Sanders,” Turner continued.