U.S. President Donald Trump is wading provocatively into a rift between a group of liberal Democratic congresswomen and House Speaker Nancy Pelosi.

Pelosi slammed Trump's tweet saying, "When @realDonaldTrump tells four American Congresswomen to go back to their countries, he reaffirms his plan to “Make America Great Again” has always been about making America white again. Our diversity is our strength and our unity is our power."

Republican Rep. Justin Amash of Michigan, a Trump critic who recently took steps to leave his party, called the remarks "racist and disgusting."

Trump was almost certainly referring to Rep. Alexandria Ocasio-Cortez of New York and her allies in what's become known as the squad. The others are Reps. Ilhan Omar of Minnesota, Ayanna Pressley of Massachusetts and Rashida Tlaib of Michigan. Only Omar, from Somalia, is foreign-born.

With his remarks, Trump again inserted himself into a rift between Pelosi and the liberal congresswomen, after offering an unsolicited defense of the Democratic speaker days earlier. Pelosi has been seeking to minimize Ocasio-Cortez's influence in recent days, prompting Ocasio-Cortez to accuse Pelosi of trying to marginalize women of color. "She is not a racist," Trump said Friday.

On Sunday, Trump's tone changed.

"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 and viciously telling the people of the United States, the greatest and most powerful Nation on earth, how our government is to be run," he said in tweets. "Why don't they go back and help fix the totally broken and crime infested places from which they came."

He added: "These places need your help badly, you can't leave fast enough. I'm sure that Nancy Pelosi would be very happy to quickly work out free travel arrangements!"

Ocasio-Cortez, who is of Puerto Rican descent, was born in the Bronx, New York, and raised in suburban Westchester County.

Pressley, the first black woman elected to the House from Massachusetts, was born in Cincinnati.

Omar, the first Somali native elected to Congress and one of its first Muslim women, was born in Somalia but spent much of her childhood in a Kenyan refugee camp as civil war tore apart her home country. She immigrated to the United States at age 12, teaching herself English by watching American TV and eventually settling with her family in Minneapolis.

Tlaib was born in Detroit.