Congresswoman Ilhan Omar has branded the US President "fascist" after crowds at a Donald Trump election rally chanted "send her back" in response to him accusing the Democrat of being part of a group of "hate-filled extremists”.

The Minnesota Representative, who came to the US as a child refugee from Somalia, told reporters in Washington: "We have condemned these racist remarks.

"I believe he (Trump) is fascist."

Referring to the chanting at the rally in North Carolina, Ms Omar said: "I want to remind people that this is what this president and his supporters have turned our country that is supposed to be a country where we allow democratic debate and dissent to take place."

She added: "This is not about me. This is about us fighting for what this country truly should be and what it deserves to be."

The President used his North Carolina campaign rally to attack the liberal views of Ms Omar, Rashida Tlaib, Alexandria Ocasio-Cortez and Ayanna Pressley, deriding them for what he painted as extreme positions and again suggesting they leave America.

Mr Trump claims he "was not happy" when his supporters chanted "send her back" in reference to Ms Omar.

Like all four of the congresswoman Ms Omar is a US citizen. The other three women were all born in the US.

The President started his attack on Ms Omar and her colleagues, all women of colour, in a tweet on Sunday, telling them to "go back and help fix the totally broken and crime infested places from which they came" over their criticism of his administration.

From left to right: Rashida Tlaib, Ilhan Omar, Alexandria Ocasio-Cortez and Ayanna Pressley. Credit: AP

“Tonight I have a suggestion for the hate-filled extremists who are constantly trying to tear our country down,” Mr Trump told the crowd in North Carolina.

“They never have anything good to say. That’s why I say, ‘Hey if you don’t like it, let ’em leave, let ’em leave’.”

During his speech, Mr Trump also accused Ms Omar of anti-Semitism, something the congresswoman has repeatedly denied.

In response to the chants, Ms Omar tweeted a Maya Angelou, the American poet, singer and civil rights activist: "You may shoot me with your words, you may cut me with your eyes, you may kill me with your hatefulness, but still, like air, I'll rise."

The four women have become known as "the squad" and have garnered attention since their arrival in January for their outspoken views and distaste for the President.

Taking the politicians on one at a time, Mr Trump ticked through a list of what he deemed offensive comments by each woman, misconstruing many facts along the way.

Ms Omar came under the harshest criticism as Mr Trump played to voters’ grievances, drawing a chant from the crowd of “Send her back! Send her back!”

President Donald Trump attacked the congresswomen's liberal views. Credit: AP

He has accused them of “spewing some of the most vile, hateful and disgusting things ever said by a politician”.

Before he left Washington, Mr Trump said he has no regrets about his ongoing row with the four.

The President told reporters he’s “winning the political argument” and “winning it by a lot”.

“If people want to leave our country, they can.

"If they don’t want to love our country, if they don’t want to fight for our country, they can (leave),” Mr Trump said.

“I’ll never change on that.”

His speech was filled with criticisms of the news media, which he says sides with liberals, and of special prosecutor Robert Mueller’s Russia probe.

Mr Mueller had been scheduled to testify to Congress on Wednesday, but it was postponed.

“What happened to me with this witch hunt should never be allowed to happen to another president,” Mr Trump said.

He also talked about illegal immigration, a main theme of his first presidential bid that is taking centre stage in his re-election campaign.

The President brushed off the criticism he has got for saying that the congresswomen should go back home.

“So controversial,” he said sarcastically.

The four politicians say they are fighting for their priorities to lower health care costs and pass a Bill addressing climate change, while his attacks are a distraction and tear at the core of America values.

The Democratic-led House of Representatives voted on Tuesday to condemn Mr Trump for what it labelled “racist comments”, despite opposition from all bar four Republicans and the President’s insistence that he does not have a “racist bone” in his body.

The condemnation carries no legal repercussions and Mr Trump’s latest harangues struck a chord with supporters in Greenville, who chanted: “Four more years!” and “Build that wall!”

It was Mr Trump’s sixth visit to the state as president and his first 2020 campaign event in North Carolina, where he defeated Democratic nominee Hillary Clinton in 2016.