In a move that elicited little surprise but much vexation, the Service Employees International Union (SEIU) — one of the more progressive unions in organized labor, principally representing public sector, health care, and building workers — announced last week it was endorsing Hillary Clinton over Bernie Sanders in the Democratic presidential primary.

SEIU has already spent some $30 million in support of Fight for 15, the organizing campaign to raise the minimum wage to $15 an hour and unionize low-wage workers. But whereas Sanders has unequivocally declared his support for a national $15 minimum wage, Clinton has said she only favors a $12 wage floor.

Why, then, did the two-million-member union go for Clinton? And what does it say about organized labor in the present and future?