After Fox News host Tucker Carlson Tuesday night launched a xenophobic tirade accusing Rep. Ilhan Omar of showing "undisguised contempt for the United States and for its people" by criticizing the nation's systemic injustices, Omar mocked Carlson as a "racist fool" and said he will "just have to get used to calling me congresswoman."

"Not gonna lie, it's kinda fun watching a racist fool like this weeping about my presence in Congress," wrote Omar, a Somali refugee and one of two Muslim women ever elected to Congress.

"No lies will stamp out my love for this country," added the congresswoman from Minnesota, "or my resolve to make our union more perfect."

Carlson's attack on Omar was described as "outrageously racist" even by his standards.

"Advertisers need to wake up," tweeted advocacy group Sleeping Giants. "By financially supporting this show and the people who rubber stamp these messages, you are sponsoring white supremacy. Full stop."

In his rant Tuesday night, Carlson described Omar as "living proof that the way we practice immigration has become dangerous to this country" and accused the Minnesota congresswoman and other migrants of "undermining" the United States.

Carlson was apparently referencing a recent Washington Post profile that quoted Omar as telling high school students, "I grew up in an extremely unjust society, and the only thing that made my family excited about coming to the United States was that the United States was supposed to be the country that guaranteed justice to all. So, I feel it necessary for me to speak about that promise that's not kept."

Watch Carlson's segment:

Andrew Lawrence, deputy director of rapid response for Media Matters for America, said he watches Carlson's show every night as part of his job. Carlson's latest tirade, Lawrence tweeted, "is probably the most racist shit this guy has said on his show and he's said a lot of racist shit."