WASHINGTON — (CNN) Mexico’s former president Vicente Fox slammed the expected meeting Wednesday between Donald Trump and the country’s current president, saying “I apologize for our president taking this step forward” and calling it “a desperate move.”

Fox lit into Enrique Peña Nieto on CNN’s “New Day” for inviting Trump to the country for a high-profile meeting, warning Penña Nieto that the meeting was a serious political risk, and continued his harsh criticism of Trump.

“I don’t understand what’s going on here, and I really apologize for our president taking this step forward,” Fox told CNN’s Chris Cuomo. “I will not understand unless there’s an explanation to it.”

“I think President Peña (Nieto) is taking an enormous political risk by hosting Trump. If he’s perceived as going soft on Trump, it will hurt him greatly. He will even be considered like a traitor because we don’t accept to be offended like we just heard, and it should not happen that he comes here with a smile on his face. I think this is a big mistake on the part of President Peña.”

Fox has made a name for himself as one of Trump’s roughest critics.

He called Trump a “false prophet” and said the GOP nominee heralded the return “to the era of the ugly American” during an interview in May.

Most famously, Fox cursed on live television while talking about Trump and his proposed border wall in February, telling Fox Business’ Maria Bartiromo, “I’m not going to pay for that f—ing wall.”

“It’s a very opportunistic move,” Fox told CNN Wednesday of the coming meeting.

“I hope US public opinion, US citizens can see this and finally, finally see what is behind Trump — this false prophet that is just cheating everybody. It’s a desperate move and I don’t see how it can work at all.”

Trump responded to Fox’s comments, taking to Twitter to say, “Former President Vicente Fox, who is railing against my visit to Mexico today, also invited me when he apologized for using the ‘f bomb.'”

Fox answered Trump’s tweet with his own, saying, “I invited you to come and apologize to all Mexicans. Stop lying! Mexico is not yours to play with, show some respect.”

Despite the invitation, Nieto has also been a vocal critic of Trump throughout the his rise to the Republican presidential nomination. He has flatly rejected Trump’s suggestion that Mexico would pay for a border wall, and even compared Trump to dictators like Benito Mussolini and Adolf Hitler in comments from March.