WASHINGTON (AP) — Top officials from the U.S. and Mexico will begin talks in a scramble to fend off President Donald Trump’s threat of devastating tariffs on the southern ally and meet his demand for fewer migrants at the border.

Trump is heading to London for a long-planned overseas trip, leaving others to stem a potential trade crisis. It’s unclear what more Mexico can do to satisfy the president. Trump’s Republican allies warn the tariffs on Mexican imports will hit U.S. consumers and harm the economy.

On Monday, Mexican Economy Minister Graciela Marquez plans talks with Commerce Secretary Wilbur Ross. Two days later, delegations led by Secretary of State Mike Pompeo and Foreign Relations Secretary Marcelo Ebrard will also meet in Washington.