U.S. House Speaker Paul Ryan has set a May 17 deadline to be notified of a new North American Free Trade Agreement to give the current U.S. Congress a chance to pass it, Reuters reported May 10.

"We have to have the paper — not just an agreement, we have to have the paper — from [the Office of the U.S. Trade Representative] by May 17 for us to vote on it this year, in December, in the lame duck" session, Ryan said before the Ripon Society in Washington on May 9. A spokeswoman said the speaker referred to a notification of intent to sign the NAFTA, and not necessarily the full text.

Ryan was pessimistic a deal could be reached in time, noting a "handful of unresolved issues" between the U.S., Canada and Mexico such as U.S. demands for more access to Canada's dairy market and to make an investment dispute arbitration system optional.

Major differences also remain over the key issue of automobiles, with Mexico launching a counter-proposal to U.S. demands to toughen automotive industry content rules and hike wages.

Mexico's Economy Minister Ildefonso Guajardo said time was running out to meet Ryan's deadline and told Reuters he expected to know by the end of May 11 "if we really have what it takes to be able to land these things in the short run." He also said that negotiators are not just tackling auto issues. "We're going over all the items. It's very important to stress that."

Canada's Foreign Minister Chrystia Freeland was more upbeat on the talks' progress but did not indicate when an agreement might be reached. "We are definitely getting closer to the final objective," she said after meetings with lawmakers in Washington, Reuters reported separately.

Guajardo, U.S. Trade Representative Robert Lighthizer and Freeland could extend their meetings into the weekend, Reuters said, citing a source close to the talks.