The ministers leading Nafta negotiations are set to wrap up the latest round of high-level talks after Canada and Mexico rejected what they see as hardline proposals by the U.S.

U.S. Trade Representative Robert Lighthizer, Mexican Economy Minister Ildefonso Guajardo and Canadian Foreign Minister Chrystia Freeland are meeting in Washington on Tuesday as battle lines form around contentious U.S. proposals. They will speak at a press conference together in the afternoon at the end of the fourth round of talks.

Mexico and Canada have repeatedly and publicly rejected the U.S. demands on dairy, autos, dispute panels, government procurement and a sunset clause. Officials familiar with the discussions describe two tracks to the negotiations -- an impasse on a few of the most contentious proposals, and progress being made on updating the pact in other areas.

On Monday, Canada flatly rejected the most recent proposal to dismantle its supply-management system for dairy. The fifth round of talks is expected to take place in early November in Mexico.