A US Democratic congresswoman has fired back, saying "I am where I belong", after supporters for US President Donald Trump chanted at a rally "send her back".

Key points: Minnesota Democrat Ilhan Omar tweets "I am where I belong" after Trump supporters chant "send her back"

Minnesota Democrat Ilhan Omar tweets "I am where I belong" after Trump supporters chant "send her back" Ms Omar is part of the self-described "squad" of Democratic congresswomen of colour which has come under attack by Mr Trump

Ms Omar is part of the self-described "squad" of Democratic congresswomen of colour which has come under attack by Mr Trump At the rally, Mr Trump said he thinks the women "hate our country"

Ilhan Omar of Minnesota — one part of the self-described "squad" whose other members are Alexandria Ocasio-Cortez of New York, Ayanna Pressley of Massachusetts and Rashida Tlaib of Michigan — was once again singled out by Mr Trump at his campaign rally in North Carolina.

Mr Trump listed a string of complaints against Ms Omar, including a false accusation she voiced pride in Al Qaeda, prompting the crowd to chant to "send her back, send her back".

Soon after the rally ended, Ms Omar responded on Twitter.

"I am where I belong, at the people's house and you're just gonna have to deal," she wrote.

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Mr Trump turned his latest campaign rally into an extended dissection of the liberal views of the four women, deriding them for what he painted as extreme positions and suggesting they just "leave".

"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, a swing state he won in 2016 and wants to claim again in 2020.

"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'."

The self-described "squad" of Democratic congresswomen of colour. ( ABC News )

Mr Trump declared: "I think in some cases they hate our country".

The Democratic 'squad' New York congresswoman Alexandria Ocasio-Cortez is of Puerto Rican descent

New York congresswoman is of Puerto Rican descent Massachusetts congresswoman Ayanna Pressley is of African-American descent

Massachusetts congresswoman is of African-American descent Michigan congresswoman Rashida Tlaib is of Palestinian descent

Michigan congresswoman is of Palestinian descent Minnesota congresswoman Ilhan Omar was born in Somalia and emigrated to the US at age 12 after spending much of her childhood in a Kenyan refugee camp

Mr Trump set off a firestorm on Sunday when he tweeted that the four should "go back" to their home countries. All were born in the US except for Ms Omar, who came to the US as a child after fleeing Somalia with her family.

Mr Trump has accused them of "spewing some of the most vile, hateful and disgusting things ever said by a politician", and he expanded on his criticisms during the rally in Greenville.

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

Among his complaints against Ms Tlaib, Mr Trump correctly reported that she had referred to the President by the "F-word", adding "that's not nice, even for me".

Mr Trump himself had unloaded a vulgarity earlier in his speech, denouncing the Russia probe of his campaign and administration as "bulls***".

Donald Trump has singled out Minnesota Democrat Ilhan Omar for criticism. ( AP: J. Scott Applewhite )

As for Ms Ocasio-Cortez, Mr Trump fumbled over her name and declared, "I don't have time to go with three different names". He then referred to her as just "Cortez" as he challenged her complaints about dire conditions at migrant detention centres at the border.

In a lighter moment, Mr Trump wondered if Ms Pressley was related to Elvis Presley, then pivoted to more serious points, claiming she thought people of colour should "think the same".

Before he left Washington, Mr Trump said he has no regrets about his ongoing spat with the four. Mr Trump told reporters he thought he was "winning the political argument" and "winning it by a lot".

"If people want to leave our country, they can," he said.

"If they don't want to love our country, if they don't want to fight for our country, they can.

"I'll never change on that."

Donald Trump has continued his attack on the "squad" of Democratic congresswomen. ( AP: Carolyn Kaster )

Trump steps up rhetoric ahead of 2020

Mr Trump's speech was also filled with trademark criticisms about the news media, which he said sides with liberals, and of special prosecutor Robert Mueller's Russia probe.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 34 seconds 34 s Donald Trump says "if you're not happy, you can leave".

Mr Mueller had been scheduled to testify on Capitol Hill, but it was postponed. Mr Trump brought him up anyway.

"What happened to me with this witch hunt should never be allowed to happen to another president," he said.

He also talked about illegal immigration, a main theme of his 2020 re-election campaign. He brushed off criticism he received for saying the four congresswomen should go back home — "so controversial," he said sarcastically.

The four congresswomen have portrayed the President as a bully who wants to "vilify" not only immigrants, but all people of colour.

They say they are fighting for their priorities to lower health care costs and pass a deal addressing climate change, while his attacks are a distraction and tear at the core of American values.

The Democratic-led US House voted on Tuesday to condemn Mr Trump for what it labelled "racist comments," despite near-solid Republican opposition and the President's own insistence that he does not have a "racist bone" in his body.

Mr Trump has not shown signs of being rattled by the House rebuke, which carries no legal repercussions, and he called an impeachment resolution that failed in Congress earlier this week "ridiculous".

ABC/AP