Trump's comments have caught the attention of Canadian producers.
U.S. President Donald Trump has delivered his most sweeping broadside at Canada, blasting the northern neighbour for trade practices he says must be corrected in three areas: energy, lumber, and dairy.
"We're also going to stand up for our dairy farmers", Trump said in Kenosha, Wisconsin.
During a stop in the Badger State on Tuesday, the president called Canada's actions "unfair" and promised to resolve the issue quickly.
Just two months ago, Trump had warmly greeted Canadian Prime Minister Justin Trudeau at the White House, assuring reporters at a joint press conference that the trade relationship between the two countries was "outstanding" and would only require some "tweaking".
Schumer said any renegotiation of NAFTA should set as its top priority the reversal of Canadian dairy pricing policies.
She says dismantling the current supply management system would be a boon to all concerned - even though there might be some short-term pain for some in the sector, who she says, could be compensated for any losses deemed a direct effect the new economic reality. Whereas he has shown if he says one thing and then actually hears good counter-arguments or good reasons why he should shift his position, he will take a different position if it's a better one, if the arguments win him over.
They say the Trump administration plans to take steps to protect the integrity of the US steel industry. "And that includes Canada", Trump told the crowd. USA farm groups say that effectively blocks American dairy exports, exacerbating a glut of milk on the American side of the border.
The Dairy Farmers of Canada said it is confident that the Canadian government will "continue to protect and defend" the country's dairy industry.
But he said the reality is dairy farmers in the United States, Europe, New Zealand and many other countries are facing hardship because their marketplaces are oversaturated with milk.
This is not the first time Canada's dairy industry has been criticised for being overly protectionist.
Conservative leadership candidate Maxime Bernier has welcomed U.S. Donald Trump's swipe at the Canadian dairy industry, saying that it's not just American farmers who are losing out.
"I understand that certain governors are speaking to certain constituencies on that".
Canada's ambassador to the United States has also come to the defence of supply management.
University of Toronto political scientist Grace Skogstad says that while the Canadian dairy sector is "vulnerable" to external trade pressures, it has weathered disputes before, including under the North American Free Trade Agreement.
With the loss of business in Canada, he said the profitability of the Aurelius plant is at risk.
"We are steadfastly committed to free trade and its benefits for the middle class".
According to the ambassador, American producers export five times more to Canada than they export to the south. Despite the strong words, MacNaughton is downplaying any talk of growing trade irritants with the United States.