Ahead of his surprise win in Michigan on Tuesday, Sanders attacked Clinton for her support of NAFTA in the 1990s, while her husband was president. A look at his television advertising in two other heavily industrial Midwest states voting next week, Ohio and Illinois, shows he is doubling down on that message.
One ad playing in both states assails "850,000 jobs [lost] to the North American Free Trade Agreement."
The message is also a significant part of his campaign stump, as well. During a swing through Cleveland on Saturday, Sanders accepted an endorsement from a labor union representing Social Security workers -- and he made sure to mention his opposition to trade deals he says have hurt American workers.
"The result is the loss of millions of decent paying jobs and a race to the bottom," he said.
Exit polling in Michigan showed six in 10 voters sided with Sanders, agreeing free trade leads to fewer jobs here.
Clinton has defended her position on free trade, saying it is necessary, but the government should also do more to crack down on countries abusing trade deals at the expense of U.S. businesses. She voted against the only trade deal, the Central American Free Trade Agreement, to come before the Senate during her time there.
Clinton initially hedged on supporting the Trans-Pacific Partnership, a trade deal negotiated by her former boss, President Barack Obama. She now says she is opposed to it, a position Sanders mocked during their Michigan debate, saying Clinton had "found religion" on the issue.