The United Auto Workers union will work with president-elect Donald Trump to renegotiate the North American Free Trade Agreement, its President Dennis Williams said on Thursday.

Williams told reporters that one reason Hillary Clinton lost was that she was blamed for NAFTA. The union opposed Trump’s candidacy, but said his “position on trade is right on.”

As a candidate, Trump vowed to force Canada and Mexico to renegotiate the trade deal.

Williams said the union believes about 32 percent of union members voted for Trump. He also backed Trump’s call for an infrastructure bill, saying it is “one of the most important things we can do.”

Williams said he would be open to tariffs on Mexican or Chinese vehicles “as an option,” but would have to evaluate the impact of tariffs on the union overall including workers at export oriented companies such as Caterpillar Inc.

Williams said the union is considering running advertisements to say “if it’s not made in America don’t buy it.”