Donald Trump stood by his negative assessment of the North American Free Trade Agreement during a Wednesday press conference with Mexican President Enrique Peña Nieto in Mexico City.

Trump said NAFTA was doing more good for Mexico than the United States and repeated his vow to revise or withdraw from the agreement if he is elected president.

"I shared my strong view that NAFTA has been a far greater benefit to Mexico than it has to the United States and that it must be improved upon to make sure that workers in both countries benefit from fair and reciprocal trade," Trump said. "We must take action to stem this tremendous outflow of jobs from our country." 

Mexico’s leader, in contrast, gave the trade deal a good review.

“My conviction is that NAFTA has been very good both for the United States and for Mexico,” Peña Nieto said.

Peña Nieto said the North American region as a whole must become more competitive, underlining that 6 million U.S. jobs depend directly on exports to Mexico.

“I don't believe trade should be considered a zero-sum game in which for one to win, the other must lose,” he said.

“NAFTA is a 22-year-old agreement that must be updated to reflect the realities of today,” Trump responded.

The GOP nominee said improvements could be made to improve pay standards and working conditions in both countries, creating "better results for all."