WASHINGTON — U.S. and Mexican officials labored for a second day Thursday to avert import tariffs that President Donald Trump is threatening to impose as he tries to strong-arm Mexico into stemming the flow of Central American migrants across America’s southern border.

Vice President Mike Pence, monitoring the talks from his travels in Pennsylvania, said the U.S. was “encouraged” by Mexico’s latest proposals but that, so far, tariffs still were set to take effect on Monday.

He added that it would be “for the president to decide” whether Mexican was doing enough to head off the tariffs. Pence said that, among other issues, negotiators had been discussing a potential agreement to make it difficult for those who enter Mexico from other countries to claim asylum in the U.S.  Mexico has long resisted that request.

Trump has threatened to impose a 5% tax on all Mexican goods beginning Monday as part of an escalating tariff regime opposed by many in his own Republican Party.

The frantic, last-minute talks underscore Trump’s chaotic approach even when decisions have enormous economic consequences for both the U.S. and its closest allies. Trump has embraced tariffs as a tool he can use as leverage against other countries, dismissing the potential harm to American consumers and manufacturers.