House Democrats plan to introduce a resolution this week condemning President Donald Trump after he attacked four high-profile liberal Democratic congresswomen of color over the weekend, saying they should "go back" to the countries they came from, according to multiple reports.

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In a letter sent Monday to fellow Democrats and obtained by Politico, House Speaker Nancy Pelosi said Trump "went beyond his own low standards using disgraceful language" in his attacks on Rep. Alexandria Ocasio-Cortez (D-NY), Rep. Rashida Tlaib (D-MI), Rep. Ilhan Omar (D-MN) and Rep. Ayanna Pressley (D-MA).

She called the president's comments "xenophobic" and said they were "meant to divide our nation."

"This morning, the President doubled down on his attack on our four colleagues, suggesting they apologize to him," she wrote. "Let me be clear, our Caucus will continue to forcefully respond to these disgusting attacks."

Pelosi said the resolution will be sponsored by Polish-born Rep. Tom Malinowski (D-NJ) and Rep. Jamie Raskin (D-MD).

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The president brushed off criticism Monday, telling reporters gathered at the White House that condemnation of his tweets "doesn't concern me because many people agree with me." He said Ocasio-Cortez, Tlaib, Omar and Pressley are "very unhappy" and "hate our country."

"I'm watching them – all they do is complain," Trump said. "So, all I'm saying is, if they want to leave, they can leave."

Trump set off a firestorm Sunday with a series of tweets attacking the freshmen congresswomen without naming them.

"So interesting to see 'Progressive' Democrat Congresswomen, who originally came from countries whose governments are a complete and total catastrophe, the worst, most corrupt and inept anywhere in the world (if they even have a functioning government at all), now loudly an viciously telling people of the United States, the greatest and most powerful Nation on earth, how our government is to be run," Trump wrote. "Why don't they go back and help fix the totally broken and crime infested places from which they came."

Of the congresswomen targeted in Trump's tweets, only one, Omar, was born outside the U.S. Omar was born in Mogadishu, Somalia, according to The Washington Post. Her family fled civil war in the country when she was a child, and she became a U.S. citizen when she was a teenager, the newspaper reported.

Ocasio-Cortez was born in New York, Tlaib was born in Detroit and Omar was born in Cincinnati, according to the Post.

It's not the first time Trump has been accused of holding racist views. In his campaign kickoff in June 2015, Trump deemed many Mexican immigrants “rapists.” In 2017, he said there were good people on “both sides” of the clash in Charlottesville, Virginia, between white supremacists and anti-racist demonstrators that left one demonstrator dead.

Repeatedly, Trump has painted arriving immigrants as an “infestation,” and he has been slow in condemning acts of violence committed by white supremacists. He also launched his political career with false claims that President Barack Obama was not born in the United States.

The Associated Press contributed to this report.