When Rep. Rashida Tlaib (D-MI) decided to boo the mentioning of Hillary Clinton’s name at a Sen. Bernie Sanders’ (I-VT) campaign rally in Iowa on Friday, she exposed two universal truths of the Democratic primary.

The first is that the fissures that erupted between Sanders and Clinton supporters in 2016 remain very much unresolved four years later, just days before voting begins in 2020. The second is that Sanders increasingly faces a difficult choice: stand beside his sharp-elbowed, oft-controversial, crew of surrogates and online supporters that helped fuel his rise or create some strategic distance in hopes of uniting the party behind his campaign.

It is a dilemma that has become far more pronounced as Sanders finds himself poised to lay claim to the Democratic Party’s presidential nomination. And it is one that will become only more difficult should he emerge as the general election candidate.