Ocasio-Cortez’s reluctance marks a break with the outsider tactics of the activist left, represented by groups like Justice Democrats. This election cycle, the organization is trying to boot not just conservative Democrats but also some liberal Democrats and to replace them with members who are more left-wing. In other words, to replicate what it pulled off against Rep. Joe Crowley in 2018 by recruiting Ocasio-Cortez.

Ocasio-Cortez’s shift coincides with turnover among top aides in her congressional office — replacing some outspoken radicals with more traditional political professionals — along with a broader reckoning on the left on how to expand Sanders’ coalition after his failure to significantly do so in the presidential primary. Some progressives have questioned whether Sanders should have softened his anti-establishment rhetoric and tried to build bridges with mainstream Democrats who voted for Hillary Clinton in 2016 rather than betting big on turning out disaffected and first-time voters.

Ocasio-Cortez’s endorsement moves are not a fluke but part of a larger change over the past several months. After her disruptive, burn-it-down early months in Congress, Ocasio-Cortez, who colleagues say is often conflict-averse in person, has increasingly been trying to work more within the system. She is building coalitions with fellow Democratic members and picking her fights more selectively.