Elizabeth Warren tried to convince AOC not to endorse Bernie Sanders in 2020 by compiling top Sanders backers' mean tweets: book

• Sen. Elizabeth Warren warned Rep. Alexandria Ocasio-Cortez about how to approach a potential 2020 primary endorsement.
• According to a new book, Warren had her team assemble a lengthy list of problematic tweets sent out by top Sanders officials.

Sen. Elizabeth Warren unsuccessfully tried to convince Rep. Alexandria Ocasio-Cortez to stay on the sidelines during 2020 presidential election by highlighting just how outspoken some of Sen. Bernie Sanders' most notable surrogates were.

"Warren was able to read Ocasio-Cortez's hesitation, and she made the case to her that endorsing Sanders would be a mistake because of the divisive surrogates like Nina Turner around him," journalist Ryan Grim wrote in his new book, "The Squad: AOC and the Hope of a Political Revolution."

According to the new book, Warren herself directed that a long list of mean tweets to be complied into a dossier that her staff then sent Ocasio-Cortez.

"She had her staff send AOC a long dossier of mean tweets from aides and surrogates like Turner, David Sirota, Briahna Joy Gray, and Shaun King," Grim wrote.

Ocasio-Cortez herself was privately concerned about "Bernie Bros" reputation that swirled around some of Sanders' online supporters. During the time in question, Sanders and Warren were fighting to become the lead progressive alternative to then-former Vice President Joe Biden. Warren, just weeks before the Iowa Democratic caucuses, would later accuse Sanders of privately telling her that a woman could not win the presidency. Sanders has vehemently denied he said such a thing.

The tweets did not deter Ocasio-Cortez, who volunteered for Sanders' 2016 presidential campaign before her earth-shattering rise to power. Her 2020 endorsement of Sanders provided a major boost for the Vermont lawmaker's campaign. Biden, who posted poor showings in earlier states, would later use the South Carolina primary to springboard back into the race and ultimately clinch the nomination.

It's unclear what tweets were highlight in this "dossier." The four Sanders supporters in question were known for her hard-nosed statements. Turner, a former Ohio state senator, later had some of her rhetoric turned against her in a congressional race that highlighted how she said voting for Biden would be like eating half a "bowl of shit."

Representatives for Warren and Ocasio-Cortez did not immediately respond to Insider's request for comment.