Donald Trump's suggestion to build a permanent wall at the U.S.-Mexico border cannot be taken seriously, former Texas Gov. Rick Perry - one of the tycoon's White House rivals - said this week.

"The idea that you're going to build a wall from Brownsville to El Paso and hang a left and go to Tijuana is just not realistic," Perry said. "Americans want results, not rhetoric," the governor added, according to the Dallas Morning News.

Unlike his fellow Texan Sen. Ted Cruz, Perry has been increasingly critical of Trump and gone so far as to slam the "Apprentice" star's views on immigration as "a toxic mix of demagoguery and nonsense." Trump had infuriated many in the Hispanic community by claiming that Mexico brought criminals and rapists to the United States.

"What Mr. Trump is offering is not conservatism, it is Trump-ism," Perry told CNN, criticizing the real estate mogul's view that states should fend for themselves on border security. "Not only is this wrong, it perpetuates the same failed policies that have left our southern border porous and vulnerable," the former governor argued.

Trump, for his part, has defended his idea of a border wall and suggested that the massive project would come at no cost to U.S. taxpayers because Mexico would fund it, the news channel noted.

If elected president, "I will build the wall and Mexico's going to pay for it and they will be happy for it," Trump argued. "Mexico is making so much money from the United States that that's going to be peanuts. And all these other characters ... don't know the first thing about how to negotiate. Trust me, Mexico will pay."

But the "Great Wall of Trump," as the candidate has dubbed his project, could turn out to be deadly for the hundreds of thousands of individuals who attempt to cross the border each year and probably would not be deterred by even the greatest of barriers, the National Journal judged.

"Any effort to seal off the border will also make conditions more dangerous for the unauthorized immigrants who still try to make it over," the magazine said, based on immigration and security experts.