NAFTA talks are entering a pivotal moment as the U.S. turns up the pressure on Canada and Mexico to radically alter the trade pact in favor of American interests.

In the run-up to the sixth round of talks now underway in Montreal, there has been plenty of saber-rattling and posturing from the three countries.

But through it all, a somewhat consistent pattern emerged: President Trump kept threatening to withdraw from the pact while Canada and Mexico suggested they’d bring fresh thinking to the table to try to resolve some of the touchiest issues.

The question now is whether they can move forward fast enough to salvage the deal before electoral politics overwhelm the agenda later this year.

“We’re reaching the danger zone right now,” said Stephen Moore, a visiting fellow at the Heritage Foundation who was an economic adviser to Trump during the 2016 campaign. “This is a pretty important meeting, because if there’s still no progress, the White House could become very frustrated and just throw up their hands and say, ‘We’re pulling out.”‘

The latest session to revamp the North American Free Trade Agreement began Sunday in Montreal and is scheduled to last through Jan. 29, making it the longest round yet. The 24-year-old trade pact is a key linchpin for the U.S., Canada and Mexico, which trade more than $1 trillion in goods annually. Any of the three can quit after six months’ notice, although Trump is the only one to regularly threaten to give it.

Trump has lately tied the talks to his push for a border wall with Mexico, while the U.S. is also growing impatient with Canada’s perceived unwillingness to compromise, according to two people familiar with the talks who spoke on the condition of anonymity.

At the same time, there are pro-NAFTA signals coming from the Trump administration, including Agriculture Secretary Sonny Perdue, who said in an interview last week that Trump shares his view that NAFTA has benefits for U.S. farmers. And signs have been mounting from Canada and Mexico that they will be more flexible in trying to score a breakthrough in talks.

Mexico hinted it could bend on automotive rules, one of the most explosive issues, while also saying that officials agree broadly on 40 percent of the pact. Canada, meanwhile, has said it will bring “new ideas” to the talks, and that several topics, known as chapters, are close to being concluded, even as Canadian officials said the chance of a U.S. exit is seen as increasing.

There are a handful of key disputes over U.S. demands. They include autos, where the U.S. wants to raise the amount of a car that must be built in the three countries to be traded under the deal. Another hot button issue includes adding a sunset clause to terminate the pact after five years unless all three countries agree to renew it.

“It’s very important to continue to make progress both with the United States and with Canada,” Mexican Finance Secretary Jose Antonio Gonzalez Anaya said on Jan. 18. “Mexico will not pay for a wall. It’s not a negotiation stance for Mexico; it’s an issue of national sovereignty and dignity.”

Canada’s chief central banker said the ongoing talks are already hurting business investment and that it’s hard to predict the impact of the death of NAFTA.

“I would believe that it would be net negative for both Canada and for the United States, but to actually quantify that is very difficult,” Governor Stephen Poloz told a news conference on Jan. 17. Prices for consumers would rise and it would reverse the “income effect” that free trade deals create by boosting purchasing power, he said.

Canadian Foreign Minister Chrystia Freeland and Mexican Economy Minister Ildefonso Guajardo will meet in Toronto on Monday. The two ministers along with U.S. Trade Representative Robert Lighthizer are scheduled to make a joint statement on the closing day of round six, while the seventh session of talks is set for February.

If the negotiations drag on too long, they could run into the political calendar. Mexico holds a presidential election on July 1 and U.S. congressional midterms take place in November. Trump indicated this month that he could be flexible with talks ahead of the Mexican election – and then repeated his threat to withdraw if he can’t reach an agreement that’s “fair” for America.

“The White House seems to have dug in its heels,” said Moore at Heritage, adding it’s possible, but not likely, Trump will lose patience and quit. “That would be a really bad outcome for the economy. I think it would send shudders through the stock market. It would create a lot of chaos.”