US, Canadian and Mexican officials have ended a week of talks without a deal to modernise NAFTA, agreeing instead to resume negotiations soon, before a deadline next week issued by US House of Representatives Speaker Paul Ryan.
The failure to secure a quick deal underscores uncertainty over the North American Free Trade Agreement, which US President Donald Trump continued to slam on Friday, labelling it "a horrible, horrible disaster for this country".
Mr Trump, who blames the 1994 pact for US manufacturing job losses to lower-cost Mexico, often threatens to walk away unless the other two member countries agree to major changes.
After meeting for barely half an hour on Friday, the top Mexican and Canadian politicians involved in the talks to update the agreement made it clear that big differences remained.
Canadian Foreign Minister Chrystia Freeland said officials would continue working in Washington while ministers returned home for consultations.
Pressure to reach a deal increased this week after Speaker Ryan said he needed to be notified of a new NAFTA by May 17 to give Congress a chance of passing it.