NAFTA negotiators are said to have wrapped up another chapter of the deal as the three ministers leading talks meet again in Washington amid a push for a deal in principle within weeks.

The U.S., Canada and Mexico said they’ve made some progress in the latest round of NAFTA talks, while America’s trade chief warned he’d like negotiations to speed up.

NAFTA talks are switching gears and slowing down as key obstacles emerge, with Canada and Mexico rejecting what they see as hard-line U.S. proposals and negotiators exchanging their strongest public barbs yet.

U.S. negotiators on Oct. 12 presented a proposal for a so-called “sunset clause” that would see the North American Free Trade Agreement expire after five years unless the parties can agree to extend it, according to two people familiar with the talks.