Donald Trump escalated his verbal attacks on four progressive Democratic congresswomen on Tuesday, accusing them of “spewing some of the most vile, hateful, and disgusting things ever said by a politician in the House or Senate”.

Trump has shown no remorse for weekend tweets that suggested the four women “go back” to their “broken and crime-infested” countries, a racist outburst that earned domestic and international condemnation.

Instead, the US president intensified his attacks on the four women of color, claiming the inflammatory tweets he sent were not racist.

There was a deeply sceptical reaction from politicians and others who have come to regard divisive bigotry as not an exception but a defining feature of his presidency.

“If you hate our Country, or if you are not happy here, you can leave!” Trump tweeted on Tuesday, adding: “Those Tweets were NOT Racist. I don’t have a Racist bone in my body! The so-called vote to be taken is a Democrat con game. Republicans should not show ‘weakness’ and fall into their trap.”

Tuesday’s tirade came less than 12 hours after the four legislators, Ilhan Omar of Minnesota, Alexandria Ocasio-Cortez of New York, Rashida Tlaib of Michigan and Ayanna Pressley of Massachusetts, held a press conference asking that Americans “do not take the bait” of Trump’s divisive rhetoric

Three of the women were born in the US, while Omar came to the country aged 12 as a refugee and took up American citizenship five years later.

Trump stepped up the attacks as congressional Democrats planned to hold a formal vote in the House of Representatives on a resolution they have drafted condemning the onslaught, with little support expected from Republicans.

Most of the Republican party’s “NeverTrump” critics have resigned, retired or been cowed into silence by his raucous supporters.

Asked if Trump’s comments were racist, the top Republican in the House, Kevin McCarthy of California, said: “This is about ideology. And the ideology of the Democratic party is socialist. This debate is going to go on for a long time.”

Even McCarthy was forced to acknowledge, “nobody believes somebody should leave the country.” But he insisted: “The president is not a racist.”

The Senate majority leader, Mitch McConnell, on Tuesday afternoon at a press conference would not condemn the president and depicted Trump’s racism as a two-sided war of words.

“I think everybody ought to tone down their rhetoric,” he said.

“The president’s not a racist. And I think the tone of all of this is not good for the country. But it’s coming from all ideological points of view … to single out any segment of this I think is a mistake.”

When asked to explain the president’s remarks, the White House adviser Kellyanne Conway asked reporter, Andrew Feinberg, what his ethnicity was.

When Feinberg said it was “not relevant”, Conway claimed it was “because you’re asking about, he said ‘originally’. He said ‘originally from’.”

In another tweet on Tuesday, Trump claimed Omar is “polling at 8%” and, mistakenly truncating her name, “Cortez at 21%”. He said Nancy Pelosi, the House speaker, had tried to push them away from the party but they “now represent” the Democratic party. With a hint at how he hopes to turn the controversy to his electoral advantage, Trump added: “See you in 2020!”

The tirade came after the four congresswoman held a joint press conference on Monday in which they accused Trump of pushing “the agenda of white nationalists” with “xenophobic bigoted remarks” and urged the public to “not take the bait”. They called him the “the occupant of our White House” instead of president and demanded his impeachment.

On Tuesday Ocasio-Cortez added in a tweet: “Hey Mr. President, remember when you bragged about sexually assaulting women, talking about feeling their breasts and genitals, because ‘when you’re a star they let you do it?’ And then you imposed… policies to make it harder for sexual assault survivors to report assault?”

Conway’s husband, George Conway, who is a prominent Trump critic, wrote in the Washington Post: “Naivete, resentment and outright racism, roiled in a toxic mix, have given us a racist president … telling four non-white members of Congress – American citizens all, three natural-born – to “go back” to the “countries” they “originally came from”? That’s racist to the core.”

Q&A What did Trump say in his racist ‘go back’ tweets? Show On 14 July Trump sent a series of tweets saying: “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. Why don’t they go back and help fix the totally broken and crime infested places from which they came. Then come back and show us how it is done. 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!” The US president did not name his targets, but the attack was directed at congresswomen Alexandria Ocasio-Cortez of New York; Ayanna Pressley of Massachusetts; Rashida Tlaib of Michigan; and Ilhan Omar of Minnesota. Only Omar, who is from Somalia, was not born in the US. Trump has subsequently launched several further attacks on the congresswoman accusing them of "foul language & racist hatred". On 16 July he tweeted that they had been "spewing some of the most vile, hateful, and disgusting things ever said by a politician in the House or Senate, & yet they get a free pass and a big embrace from the Democrat Party. Horrible anti-Israel, anti-USA, pro-terrorist & public shouting of the F...word, among many other terrible things." He also reiterated the 'go home' message, tweeting "IF YOU ARE NOT HAPPY HERE, YOU CAN LEAVE!"

Trump seemed to address the impending vote in his tweets, asking: “Why isn’t the House voting to rebuke the filthy and hate laced things they have said? Because they are the Radical Left, and the Democrats are afraid to take them on.”

Trump’s latest salvo against the four legislators, who have become known as “The Squad” on social media, also accused the Democratic party of giving them “a free pass and a big embrace”. This characterization ignores the fact that, before Trump began taking shots at the four legislators, they were primarily in the news over intra-party squabbles with Democratic leadership.

Meanwhile, political observers still struggle to make sense of Trump’s insults and debate whether they are a product of some grand strategy or the heartfelt utterings of a generally unfiltered president. In either case, the effect won’t change – and as several analysts told the Guardian, it is an effect that could bolster his re-election chances.