Democrats warned the president was “fuelling and feeding off hate” and “stoking the most despicable and disturbing currents in our society” by vilifying Ms Omar, a Somali refugee who arrived in the US as a child nearly three decades ago.
Senator Bernie Sanders said Mr Trump was “the most dangerous president in the history of our country,” while fellow 2020 election hopeful Elizabeth Warren called for him to face impeachment.
On Thursday, the president chided his supporters who chanted the statement at the rally, joining widespread criticism of the campaign crowd’s cry after fellow Republicans warned it could hurt the GOP in next year’s elections.
In a week that has corkscrewed daily with hostile exchanges over race and love of country, Mr Trump also claimed he had tried to stop the chant at a reelection event Wednesday night in North Carolina.
“I started speaking really quickly,” he told reporters. “I was not happy with it. I disagree with it.”
However, video shows the crowd’s “send her back” shouts resounded for 13 seconds as Mr Trump made no attempt to interrupt them. He paused in his speech and surveyed the scene, taking in the uproar.
Ms Omar responded on Thursday, telling reporters: “This is what this president and his supporters have turned our country” into, she said as she walked outside the US Capitol.
“This is not about me," she added. "This is about fighting about what this country truly should be and what it deserves to be.”
Additional reporting by AP. Please allow the live blog to load.
Please allow a moment for this live article to load
Donald Trump has provoked a wave of condemnation after goading the crowd at a campaign rally into racist chanting about congresswoman Ilhan Omar.
Supporters repeatedly chanted "send her back" after the US president launched his latest attack on the Democrat and three other congresswomen of colour at the event in Greenville, North Carolina, last night.
Democrats warned the president was “fuelling and feeding off hate” and “stoking the most despicable and disturbing currents in our society” by vilifying Omar, a Somali refugee who arrived in the US as a child nearly three decades ago.
Senator Bernie Sanders said Trump was “the most dangerous president in the history of our country,” while fellow 2020 election hopeful Elizabeth Warren called for him to face impeachment.
Trump first tweeted on Sunday that Ms Omar, Alexandria Ocasio-Cortez, Rashida Tlaib, and Ayanna Pressley should “go back“ to where they came from if they disagreed with his policies. All are US citizens and all except Ms Omar were born in the country.
Trump intensified his attacks on the progressive representatives at last night's rally, depicting them as “hate-filled extremists who are constantly trying to tear our country down”.
“They never have anything good to say. That’s why I say: ‘Hey, if they don’t like it, let them leave. Let them leave,’” the president said.
Trump paused speaking, looked around the room, and nodded as his supporters repeatedly chanted “send her back” at the mention of Omar’s name.
Here's my colleague Adam Withnall's write-up of last night's Trump rally:
The racist chant at last night's rally has prompted a chorus of condemnation from Democrat politicians.
A number of the party's 2020 election candidates have spoken out on Twitter, voicing disgust at the scenes in North Carolina and expressing support for Ilhan Omar.
Bernie Sanders said Trump was "stoking the most despicable and disturbing currents in society" and described him as "the most dangerous president in the history of our country. Kamala Harris said Trump's conduct "defiles the office of president," while Elizabeth Warren called for him to face impeachment and Joe Biden expressed hope that Americans would reject Trump's racism.
The majority of Americans think Donald Trump’s recent tweets attacking four Democratic congresswomen are racist and un-American, a poll has found.
Sixty-eight per cent of respondents to the USA Today/Ipsos poll said they found the president’s tweets “offensive”.
Emma Snaith has the full story:
The scenes at last night's Trump rally were reminiscent of the president’s 2016 election campaign events, at which his supporter’s chanted “lock her up” about his opponent Hillary Clinton.
But Brian Schatz, Democrat senator for Hawaii, explains why he feels the chanting about Ilhan Omar was more troubling:
Jon Favreau, Barack Obama's former speechwriter, say last night's rally was "one of the most chilling and horrifying things I’ve ever seen in politics":
Ilhan Omar herself responded to last night's racist chants by quoting Maya Angelou's "Still I Rise", a poem about resilience in the face of oppression and discrimination:
The Democrat also aimed this tweet at her critics:
Amidst the widespread condemnation of the scenes at Trump's rally in North Carolina, some are also voicing fears that the president's recent racist rhetoric could escalate into something even worse.
Here's a tweet from New York City mayor Bill de Blasio:
Brian Klass, a political scientist at University College London and Washington Post columnist, warned "the worst is yet to come" of the president's "dangerously authoritarian impulses":
Republicans in Washington largely seem to be remaining silent on Trump's Greenville rally, with almost all of the political condemnation coming from Democrats.
However, there have been a handful of conservative commentators voicing dismay about the "send her back" chant.
Former Republican congressman Joe Walsh, who has previously criticised Trump's racist tweets, called last night's scenes "ugly" and said "every Republican should condemn this bigotry immediately".
He added the president was "a horrible human being" and said he feared "it will get worse".
Conservative pundit Ben Shapiro said the chanting was "vile" and "disgusting", although he qualified his criticism by echoing Trump's claim that Ilhan Omar is a "radical antisemite".
Fox News commentator Guy Benson also laid into Omar, but said he was "sicked by the hate-laced 'send her back' chants":
Ilhan Omar is receiving support from around the world after Donald Trump's latest racist attack prompted his supporters to erupt in chants calling for her deportation.
The hashtag #IStandWithIlhan is the currently the top trending topic in the US as thousands of people post messages of solidarity.
Politicians in the UK have also voiced support for the congresswoman.
London mayor Sadiq Khan - himself a frequent target for Mr Trump's invective - said the four congresswomen targeted by Trump "represent hope for the future".
Labour MP Tulip Siddiq said the "racist rally sends shivers down my spine", while her party colleague Jess Phillips said: "This is what fascism looks like. We must fight it at home and abroad."
Ed Davey, a contender in the Liberal Democrat leadership contest, tweeted of last night's chant: "This is heartbreaking and terrifying. If we don't learn from history we are doomed to repeat it.
"All of us who stand for liberal values, and for decency, must stand up to Trump's disgusting racism and the hate he sows."
Theresa May's official spokesman said: "I don't know if the prime minister has seen it but as I said earlier in the week the president's comments in respect of the congresswomen were completely unacceptable and that remains the case."
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies