Biden has long-standing ties to labor unions and routinely talks about how the middle-class and union members built the nation.

The powerful United Auto Workers Union has yet to endorse any candidate, but its spokesman, Brian Rothenberg, said it supports the idea of universal healthcare. Sanders has made a government-run healthcare system, Medicare for All, the heart of his campaign.

“The high cost of healthcare is one of the impacts when you’re bargaining, so universal healthcare would actually give you a better ability to bargain at the table,” Rothenberg said.

Not all of Sanders’ positions play well with the state’s unions, though. In particular, he has called for the closure of a 66-year-old crude oil pipeline that runs below portions of the Great Lakes, as part of his sweeping plan to swiftly end the U.S. fossil fuel economy to fight climate change.

“It’s going to cost (Sanders) a lot of support in our union,” said Terry Gilligan, business manager of Detroit Pipefitters Local 636.