U.S. trade officials were in Mexico City last week ahead of an upcoming review of the USMCA trade deal — the treaty that keeps many goods that flow between the United States, Mexico and Canada tariff-free.

The trade pact is up for its first mandated review this July, six years after it replaced NAFTA under the first Trump administration.

President Donald Trump has said the United States isn’t ready to re-approve the treaty as is, suggesting talks could extend past July, said Chris Sands, who leads the USMCA initiative at the Brookings Institution.

The uncertainty is taking a toll on the economy, Sands said.

“Businesses are not investing as much as they would normally invest in their plant and equipment, in upgrades, in hiring new people, because they can’t assess the risk,” Sands said.

Mexican and U.S. officials said after a round of talks in Mexico City last week that formal bilateral negotiations between the two countries will start in late May.