Canada’s chief Nafta negotiator is urging U.S. businesses to step up pressure on the Trump administration to save the trade deal, as successful talks increasingly hinge on the U.S. backing off its most controversial proposals. Steve Verheul made the request on Sunday in Mexico City with about three dozen members of the U.S. Chamber of Commerce, according an official briefed on Verheul’s remarks who spoke on the condition of anonymity. Negotiators are gathered in Mexico’s capital for the fifth round of discussions to upgrade the North American Free Trade Agreement that wrap up Tuesday. Verheul previously warned the chamber to brace for life after Nafta, and the business group has been raising the alarm by highlighting the U.S. economic cost of losing the trade pact. His warning is the latest sign that discussions are bogged down amid deep divides over contentious U.S. proposals, with U.S. President Donald Trump’s regular threats to walk away looming over talks. Many American lawmakers have also been speaking out in support of Nafta, and Canada and Mexico are holding out hope that domestic pressure will lead U.S. Trade Representative Robert Lighthizer to back off controversial demands. Those include requiring cars to have 50 percent U.S. content, imposing a sunset clause on the deal, killing the Chapter 19 dispute panels and dismantling Canada’s dairy sector, which relies on a system of quotas and tariffs that Canadian officials argue prevents oversupply. “It’s hard to see any breakthrough if the U.S. does not change its attitude and does not become much more realistic with respect to their ask,” Yves Leduc, director of international trade for the Dairy Farmers of Canada lobby group, said in Mexico City on Monday. “We regularly engage with stakeholders in Canada, the U.S., and Mexico, and we will continue to maintain open channels of communication,” Alex Lawrence, a spokesman for Canadian Foreign Minister Chrystia Freeland, said in a statement. A spokesman for the the chamber declined to comment.