Simmering tensions that ran through the primary campaign between Hillary Clinton and Bernie Sanders grew to a full boil Monday as the Democrats began their national convention.

Hacked emails from the Democratic National Committee show party leaders were not necessarily neutral brokers, seemingly tilting the scales toward Clinton’s candidacy. The revelations cost the chairwoman of the Democratic Party, Debbie Wasserman Schultz, her job.

Sanders has not withdrawn his endorsement of Clinton, and is expected to reiterate his support in a speech Monday night. But will Sanders’ supporters follow suit?