Fox News anchor Shepard Smith contradicted on-air Wednesday his colleague Tucker Carlson, who claimed a day before that white supremacy is “actually not a real problem in America.”

Smith, who was covering former Vice President Joe Biden's speech on race, concluded that “white nationalism is without question a serious problem in America." U.S. President Donald Trump later attacked Smith on Twitter, writing: "Watching Fake News CNN is better than watching Shepard Smith, the lowest rated show on @FoxNews. Actually, whenever possible, I turn to @OANN!"

Trump seemed to endorse right-wing One America News Network over Fox News in the tweet.

In the segment, Smith said that Biden’s speech chronicled “the unmistakable rise of white nationalism and white racism in America.” Biden's words, Smith continued, are “calling us to our better souls, to recognize that white nationalism is real, that white nationalism is on the rise, that white nationalism is without question a very serious problem in America and beating down those who would help facilitate it and encourage it.”

Smith words were a direct contradiction to Carlson, who argued, “the whole thing is a lie,” and that the idea of it is a hoax created by the media and the left.

Carlson continued, “if you were to assemble a list, a hierarchy of concerns of problems this country faces, where would white supremacy be on the list? Right up there with Russia probably.”

“The combined membership of every white supremacist organization in this country would be able to fit inside a college football stadium,” the host concluded without citing numbers.

"Just like the Russia hoax, it's a conspiracy theory used to divide the country and keep a hold on power,'' he added. "That's exactly what's going on."

Carlson, who is a regular supporter and adviser to Trump, has himself been accused of spreading white supremacist talking points by claiming “immigrants make America poorer and dirtier” and calling for cultural preservation.

Trump is facing criticism after a white gunman apparently wrote an anti-Hispanic rant before opening fire with an AK-47-style rifle in an El Paso Walmart, killing twenty two shoppers — many of them Latino. The shooter echoed Trump's language, calling Hispanic Americans "invaders."

“I’ve lived here 50 years,” Calrson concluded. “I’ve never met anybody, not one person, who ascribes to white supremacy. I don’t know a single person who thinks that’s a good idea. They’re making this up.”