Cuomo and Walker wrote that roughly 70 NY dairy farmers and millions of dollars in sales have been impacted by new Canadian regulations that target imports of ultra-filtered milk, which is used to make cheese and yogurt.
Canada's dairy sector, which includes C$6 billion ($4.45 billion) in annual farmer milk sales, is protected by high tariffs on imports and controls on domestic production as a means of supporting prices. Trump's comments came shortly after he received a letter from Gov. Scott Walker and New York Governor Andrew Cuomo, who urged the president to take action after Canada's sudden change in dairy pricing policy resulted in almost 100 Wisconsin dairy farms being dropped from their suppliers.
Trump, however, blamed Canada for "some very unfair things have happened to our dairy farmers and others and we're going to start working on that".
MacNaughton said his intent with the letter was to correct the record following a letter critical of Canada's supply-management dairy system from the governors of Wisconsin and NY.
Trump said in Wisconsin Tuesday that he'll work on a solution.
Trump's criticism came two days after he first knocked Canada's impact on Wisconsin dairy farmers during a visit to the state on Tuesday, when he vowed the U.S. would "stand up for our dairy farmers". Many of those farms may now be forced out of business.
"How certain governors are speaking to certain constituencies on that, it's politics", Trudeau said.
"Ultimately governors and people in the states recognize the importance of our relationship and that it's two-way, and we are going to continue to build on that", McNeil said.
"So the Americans are not suffering from the current terms of NAFTA and existing trade agreements".
But Trump has repeatedly pledged to take a tough approach in order to strike better trade deals for American exporters.
"We can't let Canada or anybody else take advantage and do what they did to our workers and to our farmers", he said.
MacNaughton said the USA enjoys a dairy trade surplus with Canada.
Trump said today that the United States will report in the next two weeks what it intends to do with the North American Free Trade Agreement (NAFTA), which he has promised to renegotiate. On Tuesday, Trump vowed to resolve the trade dispute with Canada. Their processor, Grassland Dairy, says Canada will no longer buy its products and, in turn, they will stop purchasing milk from dozens of Wisconsin farmers on May 1st.
"Any increase of trade barriers between our countries would significantly impact jobs in the United States, as well as in Canada".
Trudeau signalled that he is optimistic he can persuade Trump, saying the USA president is "unlike many politicians" and avoids the instinct to "stick with" a particular position.
Next week will present another test in the U.S. "We can all agree that, it is critical to level the playing field for our hard-working dairy farmers and make sure our Canadian neighbors rescind their unfair policy and again play by the rules".
Relations with the U.S. are crucial for Canada, since more than 75 percent of its exports go to the U.S. Eighteen percent of U.S. exports go to Canada.