WASHINGTON — Senior Mexican officials launched an urgent campaign to stop President Trump’s latest tariff threat, telling the administration Monday they were doing their part to stem migration through their territory and that taxes on trade would only hurt both nations’ economies.

Marcelo Ebrard, Mexico’s foreign minister, said he was confident an agreement could be reached with the U.S. but that punitive tariffs would backfire by increasing the large numbers of Central American migrants attempting to cross the border between Mexico and the United States.

Trump last week stunned Mexicans and members of his own Cabinet by announcing he would slap a 5% tariff on goods imported from Mexico starting June 10, increasing in 5% increments steadily until October, unless the government of President Andres Manuel Lopez Obrador stops the flow of migrants into the U.S.

Ebrard, speaking to reporters in Washington, did not outline new proposals to present to Trump administration officials but instead warned of dire consequences with Trump’s proposal.

“Tariffs, along with cuts of financial aid to northern Central American countries,” Ebrard said, “would be counterproductive, would not address migration flows and could reduce Mexico’s capacity to give alternatives to migrants.”

Over the last couple of years, most of those migrants have been Central Americans fleeing violence and poverty in Honduras, El Salvador and Guatemala and claiming asylum from persecution in the U.S., which is legal under U.S. law. Illegal immigration from Mexico itself has declined sharply from earlier levels.

Trump, however, blames Mexico for failing to close its southern border to the Central Americans.

Mexico is one of the United States’ largest trading partners, and tariffs would increase prices for consumers on a wide range of products, including automobiles, washing machines, avocados, fresh fruits, clothing and beer.

The president has also announced plans to cut financial aid to the three countries, known as Central America’s northern triangle, where violence and poverty have robbed many residents of a future.

Mexico says those policies are misguided. Echoing Lopez Obrador, Ebrard said the focus should be on root causes of migration and finding ways to build up economies and security in Central America.

He also said Mexico was already taking the measures the Trump administration had demanded of it, including the acceptance of migrants back into Mexico from the U.S. to await the adjudication of amnesty claims — a process that can take well over a year — and the rounding up and deportation of thousands more.

U.S. officials said Mexico could do a lot more, especially on its porous southern frontier.

“Punitive actions alone won’t work; it’s not working,” Ebrard said. “We already have made a great effort.”

Without those efforts, Ebrard and his team said, a quarter of a million migrants could enter the U.S. over its southern border this year.

The Mexican argument picked up some support Monday from a leading Republican, Sen. John Cornyn of Texas.

“I appreciate President Trump’s unwavering commitment to securing our southern border and enforcing our immigration laws,” Cornyn said in a statement. “But it’s important to remember that any actions that we take to secure our southern border must also keep in mind the important role that Mexico plays in the economy of the United States.”

Ebrard arrived in Washington late Friday and spent the weekend huddled with other members of his government to plot strategy. He is accompanied by Mexico’s economy minister, Graciela Marquez; agriculture minister, Victor Villalobos; and several officials from the foreign ministry.

Meetings were planned with Agriculture Secretary Sonny Perdue, Commerce Secretary Wilbur Ross, acting head of the Department of Homeland Security, Kevin McAleenan, and U.S. Trade Representative Robert Lighthizer.

Ebrard said he intended to meet with Secretary of State Michael R. Pompeo on Wednesday when Pompeo returned from a state visit to Britain. The State Department, however, has not confirmed that, and nothing appears on the secretary’s schedule for that day.

Also absent from Washington are Trump, who is in Britain, and Jared Kushner, the president’s son-in-law and advisor, who has frequently served as interlocutor between Mexico and the White House.

Ebrard made hurried phone calls to Pompeo and Kushner on Friday, ahead of his trip to Washington, and hoped to enlist them to persuade Trump to back down on the tariffs. On Sunday, however, Trump’s chief of staff, Mick Mulvaney, insisted that the president was “deadly serious” about the tariffs and that he expected at least the first round of 5% to go into effect.

Ebrard was just in Washington two weeks ago, when he thought he and U.S. officials had agreed on development plans for Central America that now seem doomed.

Asked what strategy he could employ now, he said: “Diplomacy; we have 200 years of diplomacy with the United States.”

“We need to continue doing exactly what we were doing just last week,” said Jesus Seade, deputy foreign minister for North American affairs. “This is an enormous boulder in our path and will jeopardize both our economies.”

Ebrard would not discuss concessions that his government might be willing to make, except to say Mexico continued to oppose being declared a “safe third country,” which would require those seeking asylum in the U.S. to make their applications in Mexico without ever reaching U.S. territory. The Trump administration has been advocating that idea because it probably would dramatically decrease the number of asylum cases.

Ebrard and his team echoed the assessment of Republican lawmakers and others who warned the tariff dispute hurts chances to ratify the new U.S.-Mexico-Canada trade agreement, drafted as an updated version of NAFTA and championed by Trump.

Lopez Obrador so far has not responded in kind to Trump’s threatening tone, insisting that despite the president’s belligerent rhetoric, the Mexican government wants to remain a friend to the United States.

“We are not going to get caught up in a confrontation,” Lopez Obrador repeated Monday in Mexico City. “We continue considering the U.S. government to be a friend of the government of Mexico, and I want to continue being a friend of President Donald Trump.”

The two have never met, but Trump is said to admire what is sometimes described as Lopez Obrador’s iconoclastic style. He came to office in December. His predecessor, Enrique Peña Nieto, suffered in both popularity and credibility for his dealings with Trump, when he was not seen as being sufficiently tough in front of Trump’s insults and challenges.

Lopez Obrador, by contrast, has extremely high approval ratings, allowing him more maneuvering room than Peña Nieto.

“To Lopez Obrador’s credit, he immediately worked to reduce the tensions,” Ian Bremmer, president of the Eurasia risk assessment group, reported Monday, fresh from meetings in Mexico City. Lopez Obrador is “not wanting a fight that he has no capacity to win and will only hurt his economy further.”