President Donald Trump’s top NAFTA negotiator canceled his participation in the Summit of the Americas that begins Friday, following in his boss’s footsteps and casting doubt on when trade ministers will next be able to meet to discuss the accord.

U.S. Trade Representative Robert Lighthizer will no longer attend the meeting in Lima, spokeswoman Emily Davis said in an emailed response to questions, citing a change in schedule. Deputy C.J. Mahoney will go in his place, Davis said.

Lighthizer’s decision comes after the announcement on Monday that Trump was canceling his trip to the summit as he contemplates a military response to an alleged chemical weapons attack in Syria. The Trump administration last week was pushing to announce a framework NAFTA deal at the summit.

Lighthizer on Thursday will discuss trade at a White House meeting, his spokeswoman said. Senate Agriculture Committee Chairman Pat Roberts said he’ll be at the meeting, and will encourage the administration to increase trade rather than expand farm subsidies that Trump has proposed. Senator John Cornyn, the chamber’s no. 2 Republican, said he heard “encouraging words” that a Nafta deal is close when he dined with Trump on Wednesday.

Lighthizer had planned to meet with Canadian Foreign Minister Chrystia Freeland and Mexican Economy Minister Ildefonso Guajardo on the sidelines of the Peru summit to discuss Nafta negotiations happening this week in Washington, three people familiar with the talks said yesterday. It’s unclear when Lighthizer, Guajardo and Freeland, who met in Washington last week, will be able to meet again, in part because Guajardo is scheduled to travel to Europe for trade talks with the European Union, according to a person familiar with his plans.

Vice President Mike Pence will attend the summit along with the president’s daughter Ivanka Trump and her husband and U.S. presidential adviser Jared Kushner. The summit takes place Friday and Saturday, and Nafta technical talks in Washington are expected to run through the weekend. Guajardo on Monday said he sees an 80 percent chance of an initial Nafta agreement by the first week of May.

The latest negotiating round began Tuesday, with the issue of rules of origin set for three days of discussion beginning Wednesday. Rules of origin for the auto sector in particular, which govern what share of a typical car must be North American-made to be traded tariff-free, are arguably the biggest sticking point in negotiations that began in August.

--With assistance from Erik Wasson