Trade ministers at the Trans Pacific Partnership talks in Atlanta have extended negotiations until the weekend, in a bid to get a final agreement.
Mexico's Economy Minister Ildefonso Guajardo said no-one from the 12 nations at the talks wanted to leave without an agreement.
Japan's Economy Minister Akira Amari said they were starting to see the path to an agreement and have agreed to make final efforts.
Several officials said a final deal could come quickly depending on the outcome of bilateral talks on intellectual property protection for medicines and trade in dairy products and vehicles.
The monopoly period for biologic drugs, which are made from living cells, was the most difficult issue remaining, Mr Amari said.
That has implications for the price of medicines in New Zealand.