President Trump on Tuesday called for fixing NAFTA or dumping it, saying that it is a "one-sided deal against the U.S."

"We are going to make some very big changes or we're going to get rid of NAFTA once and for all. It cannot continue like this, believe me," he told workers at a tool factory in Kenosha, Wis.

Trump specifically talked about Wisconsin dairy farmers, who are losing business in a trade war with Canada. The U.S. is going to "stand up for dairy farmers in Wisconsin" and said that he is going to demand "fair trade with all our trading partners, and that includes Canada."

"Because in Canada, some very unfair things have happened to our dairy farmers," he said.

NAFTA eliminated many tariffs between the U.S. and Canada. That included ultrafiltered milk, used to make cheese, which hit the market in 1994. Ontario farmers cut the prices on their milk, hurting sales of their U.S. competitors, and other provinces plan to follow suit. Canada says U.S. farmers have built an oversupply that is driving down prices.

Trump cautioned that the changes to NAFTA and other trade deals could not happen overnight. He said that the administration had attempted to renegotiate NAFTA terms with Mexico "immediately" but were hamstrung.

"We have these provisions were you have to wait long periods of time. You have to notify Congress and after you notify Congress you have to get certified and then you cannot speak to them for 100 days. The whole thing is ridiculous," he said.