HOUSTON -- Former Mexican President Vicente Fox is making his position clear on Donald Trump's pledge to make Mexico pay for a wall along the U.S.-Mexico border.
"I'm not going to pay for that f***ing wall. He should pay for it. He's got the money," Fox told Fusion's Jorge Ramos in an interview published Thursday.
Trump quickly responded on Twitter.
FMR PRES of Mexico, Vicente Fox horribly used the F word when discussing the wall. He must apologize! If I did that there would be a uproar!
— Donald J. Trump (@realDonaldTrump) February 25, 2016
During Thursday's Republican debate in Houston, Trump was asked about Fox's comments.
"The wall just got 10 feet taller, believe me," he said. "This guy used a filthy, disgusting word on television, and he should be ashamed of himself and he should apologize, OK?
"Now, the wall is $10 billion to $12 billion, if I do it. If these guys do it, it will end up costing $200 billion. But the wall is $10 billion to $12 billion."
Republican candidate Marco Rubio responded by saying, "If he builds the wall the way he built Trump Towers, he'll be using illegal immigrant labor to do it."
Responded Trump: "So cute. Such a cute sound bite. ... You don't know a thing about business."
Added Rubio: "Here's the guy that inherited $200 million. If he hadn't inherited $200 million, you know where Donald Trump would be right now? Selling watches."
Fox, who was president from 2000 to 2006, also pushed back on Trump's claim that he was winning support among Latinos, after entrance polls at Tuesday's Nevada caucuses showed him winning Latino Republican caucusgoers.
"Please, you Hispanics, Latinos in the U.S., open your eyes. It's not to defend our race. Not to defend our creed. It's to defend this very same nation that is hosting you. This nation is going to fail if it goes into the hands of a crazy guy," Fox told Fusion.
Trump has often insisted he will build a wall along the border and convince Mexico to pay for it.
The promise is a staple of his campaign and has often been turned into a call-and-response at his rallies, where he asks supporters who will pay for the wall and they yell back, "Mexico!"
Pope Francis said last week that Trump "is not Christian" if he seeks to build a wall and deport undocumented immigrants.