“We have the opportunity to share our point of view, explain why the Mexican position, that we are following regarding this issue, and tomorrow we are going to follow the talks,” he said.

He added that the dialogue focused on Mexico’s proposals on migration, rather than the tariffs.

While Mr. Trump insists he is committed to imposing tariffs, the president faces intense opposition not only from Democrats, but also from business executives, economists and members of his own party, who say tariffs are the wrong approach to dealing with immigration issues. Republican senators have been mobilizing to prevent the White House from moving ahead with tariffs, warning Mr. Trump that they are almost uniformly opposed to his plans to tax Mexican imports.

At a lunchtime briefing on Tuesday, Senator Mitch McConnell of Kentucky, the majority leader, told administration lawyers that Republican senators needed to hear directly from Mr. Trump before he slapped tariffs on Mexico, according to two Republican officials familiar with the discussion.

In the closed-door lunch off the Senate floor, several Republicans complained bitterly about the tariffs, arguing they would harm their constituents and the economy while doing nothing to improve the immigration problems at the border. Many of them were irritated that the discussion about a major policy move that could take effect within days was unfolding at a time when the president was abroad, and that the administration sent two lower-level lawyers who could not answer basic questions about the tariffs to Capitol Hill to brief them.

Mr. McConnell asked the lawyers when the tariffs would go into effect. When they answered June 10, Mr. McConnell replied, “O.K., Monday,” and said Republican senators would need to hear from the president before then. Mr. Trump is scheduled to return from his European trip on Friday.

Across the globe, world leaders are trying to take steps to mollify Mr. Trump. In recent days, Guatemalan officials signed a cooperation agreement with United States officials to deploy about 80 Border Patrol agents and Department of Homeland Security investigators to Guatemala to advise on screening families and children crossing the border. The authorities will also help build out interior checkpoints.