All the candidates are vying for the attention and support of the powerful casino workers culinary union, whose 60,000 members are mostly women and mostly immigrants.
Biden snapped up an early endorsement from the union's former political director, state Sen. Yvanna Cancela, but so far the union has not said if it will endorse in the primary contest.
Among the issues the union is eyeing closely is the fight over "Medicare for All." The union spent years negotiating a strong health plan for its members, sacrificing wage increases and other benefits along the way. Unions aren't eager to give all that up for a government-run health system.
Ted Pappageorge, the culinary union's president, has called those proposals, backed by Sanders and Warren, "potentially problematic" for the union members who want to keep their current health plans.