“What exists is a conversation about what do to with 9,000 people that are going to remain in Tijuana for a year,” said Mr. Ebrard, who acknowledged the discussions were ongoing. “What we are trying to think about is how to organize this, but we still have not found the response.”

Assistant United States Secretary of State Kimberly Breier said Saturday: “Our engagement with Mexico is, first and foremost, based on mutual respect and on a commitment to work together to find creative solutions to our shared challenges. We continue to work closely with both the current and incoming Mexican governments on issues across the bilateral relationship, including illegal migration.”

Sunday’s meeting is to include Mr. Ebrard; the incoming interior minister, Olga Sanchez Cordero, and other top officials in the government of President-elect Andres Manuel Lopez Obrador.

News of the proposal was first reported by The Washington Post, which quoted Mrs. Sanchez Cordero as saying an agreement between the United States and the incoming Mexican government had been reached. But later Saturday, Mrs. Sanchez Cordero issued a statement saying that there was no decision regarding the use of Mexico as a holding area for asylum applicants to the United States.

The Trump administration, eager to lower migration numbers and ease the burden on the American asylum system, had suggested turning Mexico into a so-called “safe third country,” which would require migrants who pass through there with the intention of applying for asylum in the United States to petition for sanctuary in Mexico instead.

But the outgoing administration of President Enrique Peña Nieto has resisted, as has its successor.

“We still do not have a specific proposal from the United States,” Mr. Ebrard said. “We are still against the safe third country, but this theme is something distinct and because of that, we are analyzing it with care.”