The latest Nafta talks are nearing conclusion without a major breakthrough or agreements on even the least-contentious topics, officials familiar with the negotiations say, fueling doubts among observers that a deal can be reached this year.

U.S. Trade Representative Robert Lighthizer is scheduled to speak publicly alongside Mexican Economy Minister Ildefonso Guajardo and Canadian Foreign Minister Chrystia Freeland Tuesday to conclude the second round of talks toward a new North American Free Trade Agreement. Their appearance will cap a five-day session in Mexico City.

While negotiators have made some progress, they have yet to agree on any major contentious issue and are far from a deal on individual Nafta chapters, the officials said, asking not to be identified discussing private matters. On some topics, discussion has been verbal with no specific text proposals submitted, they said.