President Donald Trump speaks during a news conference with British Prime Minister Theresa May at the Foreign Office, June 4, 2019, in central London.
President Donald Trump speaks during a news conference with British Prime Minister Theresa May at the Foreign Office, June 4, 2019, in central London.

VOA's Michael Bowman contributed to this story.

U.S. President Donald Trump said Tuesday that it is "more likely" than not that next week he will impose a new 5% tariff on imported products from Mexico.

Trump offered his assessment at a London news conference alongside British Prime Minister Theresa May, even as U.S. and Mexican officials continued talks in Washington about the tariffs and the surge of Central American migrants traveling through Mexico to reach the United States that Trump wants to block.

"Mexico should step up and stop this invasion into our country," Trump said, contending that "millions and millions" of undocumented migrants from Guatemala, Honduras and El Salvador are entering the U.S. to escape poverty and violence in their homelands.

"I think Mexico will step up and do what they need to," Trump said. "I want to see security at our border and great trade."

He said, "We are going to see if we can do something, but I think it's more likely the tariffs go on [next Monday], and we will probably be talking during the time that the tariffs are on."

Trump has threatened to increase the tariffs monthly in 5% increments if the migration is not curbed.

In the U.S., some Republican lawmakers, normally political allies of Trump, are opening discussions on whether to try to pass legislation to block his imposition of the 5% tariff, fearing the extra taxation would be passed on to U.S. consumers in the form of higher retail prices on an array of goods, including automobiles and farm produce.

But Trump said, "I think if they do that, it's foolish," citing his high political standing among Republican voters, even as surveys in the U.S. show that overall, American voters disapprove of his performance as president.

Talks between the two countries started Monday, with U.S. Secretary of State Mike Pompeo set to meet Wednesday at the White House with his Mexican counterpart, Foreign Minister Marcelo Ebrard, along with other U.S. and Mexican officials.

Marcelo Ebrard
Mexico's Foreign Minister Marcelo Ebrard speaks during a news conference about the ongoing trade negotiations with the U.S., at the Mexican Embassy in Washington, June 4, 2019.

Ebrard said Tuesday he believes a deal can be reached to avert imposition of the tariffs, but if not, Mexico plans to announce its response on Thursday. It remains unclear exactly what the Trump administration would consider sufficient migration control to not impose the tariffs.

Mexico warned Monday that Trump's threatened new tariff would hurt both countries' economies and cause even more Central American migrants to travel through Mexico to reach the United States.

At the start of talks in Washington, Mexican officials said they could only go so far in meeting Trump's demand to block migrants' passage through Mexico. The officials specifically ruled out a "third safe country" agreement requiring U.S. asylum-seekers to first apply for refuge in Mexico.

Asylum-seekers from Guatemala board a Greyhound bu
Asylum-seekers from Guatemala board a Greyhound bus in El Paso, Texas, April 2, 2019. They say they spent four days sleeping on rocks under a bridge in a detention area that U.S. immigration officials have since dismantled.

"There is a clear limit to what we can negotiate, and the limit is Mexican dignity," said Mexico's ambassador to the United States, Martha Barcena.

Barcena added that U.S. tariffs "could cause financial and economic instability," reducing Mexico's capacity to address the flow of migrants and "offer alternatives" to people fleeing the three Central American countries.

Mexican officials contended that an additional quarter million migrants could try to reach the U.S. if the tariff is imposed, on top of the tens of thousands already reaching the southern U.S. border each month.

U.S. lawmakers returning to Washington after a week-long congressional recess sharply criticized Trump's latest tariff tactic aimed at a major U.S. trading partner.

"This [tariffs] is not a popular concept," Republican Sen. John Cornyn said of public opinion in Texas, which he represents. "Mexico is our biggest export market."

Another Republican, Missouri Sen. Roy Blunt, expressed concerns that trade friction could harm a newly negotiated free trade pact between the United States, Mexico and Canada.

FILE - Matt Mandel, VP Operations, views tomatoes
FILE - Matt Mandel, VP Operations, views tomatoes at SunFed produce packing and shipping warehouse in Nogales, Arizona, Jan. 30, 2017. For up to 16 hours a day, tomatoes, peppers, cucumbers and mangoes grown in Mexico flow north through a border checkpoint into Nogales, Arizona, helping to ensure a year-round supply of fresh produce across the United States.

"I'm not a big advocate of tariffs, and I'd like to get the USMCA agreement approved," Blunt told VOA. "I don't see how the addition of a tariff [on Mexican goods] right now helps make that happen."

"Mexico is a critical trading partner of the United States," Democratic Sen. Ben Cardin of Maryland said. "You put up barriers, it's going to end up costing us jobs, and it's going to cost consumers."

Cardin added that Trump's threatened tariff "would be counterproductive," as far as boosting U.S. border security.

"If we need cooperation on the southern border, they [Mexican officials] are not going to give us cooperation. Why bother if we're going to have an antagonistic relationship?" Cardin said.