Trump plans to renegotiate NAFTA but may scrap it if 'fair deal' not reached

President Donald Trump has decided that the U.S. will renegotiate the North American Free Trade Agreement but is still considering scrapping the pact if a "fair deal" is not reached with Mexico and Canada.

"I was going to terminate NAFTA as of two or three days from now," he said during a meeting at the White House with Argentinian President Mauricio Macri today.

According to Trump, the threat of ending the trade deal led to calls yesterday from Canadian Prime Minister Justin Trudeau and Mexican President Enrique Pena Nieto.

"They said, 'Rather than terminate NAFTA, could you please renegotiate?'" Trump recounted. "I said, 'I will hold on the termination. Let's see if we can make it a fair deal.'"

Trump added, "I like them very much. I respect their countries very much. Their relationship is very special."

He reminded reporters that renegotiating NAFTA was a key campaign promise and added that if he's "unable to make a fair deal ... I will terminate NAFTA."

"We have to make a deal that's fair for the United States. They understand that," Trump said. "So I've decided rather than terminating NAFTA - which would be a pretty big, you know, shock to the system - we will renegotiate."

Asked later during a working luncheon in the Cabinet Room when the renegotiation of NAFTA would begin, Trump said, "It'll start very soon. It's actually starting today."

White House press secretary Sean Spicer elaborated on Trump's position on NAFTA.

"The president also made it clear if they are unable to agree on a deal that is fair to American workers and companies, after giving renegotiation a good shot, he will move forward with termination," Spicer said.

Earlier Wednesday, an administration official told ABC News that the White House would not comment on rumors that a NAFTA executive order was in the works.

"I would say that NAFTA has obviously been a top priority for the president from Day One, and it's safe to say we've been working on addressing the issues with it since the beginning," the official said.

While campaigning for president, Trump slammed NAFTA as a "disaster" and the "worst trade deal in history."

As president, he has continued to speak out against the trade deal, last week calling it "very, very bad" for American companies and workers.

"We're going to make some very big changes, or we're going to get rid of NAFTA once and for all," he said during a speech in Kenosha, Wisconsin, earlier this month. "It cannot continue like this, believe me."

The trade agreement was signed by President Bill Clinton in 1993 and implemented in 1994. NAFTA expanded trade among the U.S., Canada and Mexico, eliminating tariffs on most goods traded among the three countries.

"President Trump agreed not to terminate NAFTA at this time, and the leaders agreed to proceed swiftly, according to their required internal procedures, to enable the renegotiation of the NAFTA deal to the benefit of all three countries," said a White House readout of calls among the leaders on Wednesday.

According to the readout, Trump said, "It is my privilege to bring NAFTA up to date through renegotiation. It is an honor to deal with both President Pena Nieto and Prime Minister Trudeau, and I believe that the end result will make all three countries stronger and better."

A summary from Pena Nieto's office echoed the White House readout. "The leaders agreed on the benefit of maintaining the North American Free Trade Agreement and work together with Canada to carry out a successful renegotiation for the benefit of the three countries," it read.

A readout released by Trudeau's office several hours earlier was sparser, saying that Trudeau and Trump "continued their dialogue on Canada-U.S. trade relations, with the prime minister reinforcing the importance of stability and job growth in our trade relations."

ABC News' Veronica Stracqualursi and Tom Kutsch contributed to this report.