Blame Canada. That’s what U.S. farmers say about some of the bubbling gluts weighing on the milk market, and they are eager for President Donald Trump to do something about it. While growers and exporters of U.S. crops and food products have expressed anxiety over Trump’s restrictive immigration policies and determination to renegotiate trade deals, dairies see him as an opportunity to crack what they see as Canada’s protectionist milk practices and to help ease oversupply in some regions. A key battleground is the little known market for ultrafiltered milk, a concentrated ingredient used to boost protein content in cheese and yogurt. Canada is creating incentives for processors to buy from domestic manufacturers. U.S. producers say that could be a disaster, and they allege the new policy would violate trade agreements. Companies in Wisconsin and New York alone might lose $150 million in sales north of the border.