Paul Ryan says he needs notice of a Nafta deal by May 17 if the current Congress is going to be able to vote on it, suggesting talks are pushing up against the constraints of U.S. trade law, even as President Donald Trump continues to deride the existing pact.

Trump repeated his disdain for the North American Free Trade Agreement on Friday, telling auto executives that he’d “never been a Nafta fan” and calling it “one of the worst trade deals in history” during a meeting at the White House.

“Nafta has been a horrible, horrible disaster for this country,” Trump said, recycling rhetoric he’s used since he started his presidential campaign in 2015. “We’ll see if we can make it reasonable.”

Ryan, the House Speaker, said on May 9 that U.S. Trade Promotion Authority regulations mean next week is a deadline for the Trump administration if it wants to pass a new agreement before the next Congress is sworn in.

“As the author of TPA, I can tell you, we have to have the paper—not just an agreement, we have to have the paper—from USTR by May 17 for us to vote on it this year, in December, in the lame duck,” Ryan said at an event hosted by the Ripon Society, a Republican policy group, according to video posted online Thursday.

Next Steps

“So it is May 9th,” Ryan said, checking his watch, shrugging his shoulders and saying with a chuckle that he would let others draw conclusions about the feasibility of meeting that deadline.

Ryan was referring to the next step of Nafta talks, spokeswoman Ashlee Strong said. If a deal is reached, the Trump administration would send a letter to Congress giving 90 days notice of its intent to sign a deal, and text of a deal must be published 30 days after that. “This is not a statutory deadline, but a timeline and calendar deadline,” Strong said by email.

Negotiators are working to meet that goal, but they won’t sacrifice quality for timing, Mexican Economy Minister Ildefonso Guajardo told reporters on Friday outside the U.S. Trade Representative’s office in Washington.

The comments put the firmest deadline yet on Nafta talks—but it may not actually be that firm. Many trade observers have said U.S. deadlines are murky, and that a deal reached later in May or even in June could theoretically get passed.

USTR Robert Lighthizer has indicated he needs a deal this month but hasn’t publicly identified a particular date. Congressional staff on committees responsible for trade, speaking on condition of anonymity, said Thursday they weren’t aware of a hard deadline for the administration to give Congress text of the agreement.

Ryan highlighted unresolved issues, such as investor-state dispute panels that he favors but Lighthizer wants to water down, and agriculture, a key sector in the Speaker’s home state of Wisconsin. He appeared to be skeptical a deal could be completed in time.

“I don’t want to make news, but um, we’ll see if they can get this done by May 17 and get us the paper to Congress, which then we could have this vote in December. If they can’t, then we won’t,” he said, adding, “May 17th, you’ll find out.”

Political Calculus

The existing Nafta remains on the books unless a country withdraws, which would require six months notice. No country has given that notice, though Trump has threatened to do so. Lighthizer has said the political calculus for passing a new Nafta would change if it had to be voted on by the next Congress.

Ryan met Thursday with Canadian Foreign Minister Chrystia Freeland in Washington, and the two discussed U.S. trade law and the impending timelines. A Nafta deal “will take as long as it takes,” she said. Freeland was twice asked Thursday by reporters whether Ryan mentioned a deadline of next week, and didn’t specifically answer.

“I think the rules are set out quite clearly in the TPA legislation, and it was certainly useful for me to hear directly from some of the people who actually wrote it how they see that process playing out,” she said. When pressed, Freeland added: “We discussed how the TPA legislation could come into play.”