WASHINGTON — A top White House aide said Sunday that President Trump is “absolutely, deadly serious” about imposing a 5 percent tariff on Mexican goods next week in a bid to stop migrants from reaching America’s southern border, brushing aside Wall Street jitters, warnings by some GOP lawmakers and reported misgivings by senior White House aides.

The bellicose tone by Mick Mulvaney, the acting White House chief of staff, dampened speculation that the two sides might reach a compromise in coming days to avert a confrontation that could hurt the Mexican economy, penalize U.S. consumers and manufacturers, and potentially drive more migrants northward.

Trump “is absolutely, deadly serious,” Mulvaney said on “Fox News Sunday. “I fully expect these tariffs to go on to at least the 5 percent level on June 10. The president is deadly serious about fixing the situation at the southern border.”

The White House announced Thursday that the import tax will increase by 5 percent every month through October, topping out at 25 percent, unless Mexico takes significant action to stem the flow of migrants, mostly from Central America, who have surged to the U.S. border in recent months.

Mulvaney refused to say precisely what the White House wants Mexico to do, a tactic that may give both sides considerable room for political maneuvering going forward.

“We intentionally left the declaration sort of ad hoc,” he said.

“So, there’s no specific target, there’s no specific percent, but things have to get better,” he added. “They have to get dramatically better and they have to get better quickly.”

Mexico’s foreign minister, Marcelo Ebrard, rushed to Washington after the surprise announcement and will lead a delegation to meet with Secretary of State Michael R. Pompeo and other U.S. officials on Wednesday, after Pompeo gets back from Europe.

White House officials have expressed confidence that the Mexican delegation would present proposals for helping stem the migrant flow, giving Trump a much-needed win on an issue that is central to his 2020 reelection bid.

Mexico’s president, Andres Manuel Lopez Obrador, said he expected “good results” from the talks, and hinted his government may do more to block organized smuggling routes that have funneled hundreds of thousands of Central Americans toward the U.S. border.

In a news conference Saturday in Veracruz, Lopez Obrador said Mexico could step up its migration enforcement measures in order to reach a deal with the White House.

“The main thing is to inform about what we’re already doing on the migration issue, and if it’s necessary to reinforce these measures without violating human rights, we could be prepared to reach that deal,” Lopez Obrador said.

Lopez Obrador, who took office in December, said his government had a “plan” to ease the economic disruption in case Trump imposes the tariffs, although he did not provide any details.

“We’re doing all we can to reach a deal through dialogue,” he said. “We’re not going to get into a trade war, a war of tariffs and of taxes.”

Trump, who first made the tariff threat on Twitter on Thursday, repeated it Sunday, tweeting that Mexico is an “ ‘abuser’ of the United States.” He added, “America has had enough.”

Many economists have publicly disputed the president’s understanding of how tariffs work. In an escalating trade confrontation with China, Trump has repeatedly claimed that Beijing, not American consumers, would bear the costs of tariffs on Chinese imports.

Business leaders, including Detroit automakers and big agriculture, have warned that the tariffs will be passed to U.S. consumers in the way of higher prices for cars, dishwashers, fruit and other household goods.

Mulvaney appeared to dismiss those concerns Sunday.

“American consumers will not pay for the burden of these tariffs,” he said, adding that “there’s already a price” in the form of “hundreds of billion dollars” for immigrants in the country illegally.