Donald Trump has insisted he has “not a racist bone in my body” as the row over his comments on social media about four Democratic Congresswomen raged on.

The US President appealed to fellow Republicans to "not show weakness" and to resist a House resolution condemning his words.

"Those Tweets were NOT Racist," declared Mr Trump on Twitter, a reference to his weekend remarks about the four female Democrats, who, he urged to "go back" to their "broken and crime-infested" countries.

The tweets, which have been widely denounced as racist, were directed at Representatives Ilhan Omar, Alexandria Ocasio-Cortez, Ayanna Pressley and Rashida Tlaib. All are American citizens with three of the four of them born in the US.

Under pressure, Mr Trump doubled down on his comments, alleging again on Tuesday that the women, who strongly oppose his policies and comments, "hate our country".

He tweeted: “I don't have a racist bone in my body!" claiming that "many people agree" with his assessment of the four politicians.

In response, independent MP Nick Boles, formerly a Conservative, replied: "No racist bones, you say? Then I guess it must be your racist soul, your racist heart, your racist hair and your strangely orange racist skin..."

The latest episode served notice that Mr Trump is willing to again rely on incendiary rhetoric on issues of race and immigration to preserve his political base in the lead-up to the 2020 election.

He shrugged off the criticism, saying: "It doesn't concern me because many people agree with me. A lot of people love it, by the way."

But the four female politicians have hit back, condemning what they called "xenophobic bigoted remarks" and renewing calls for Democrats to begin impeachment proceedings.

The Herald: Camley's Cartoon: Trump under fire over 'go home' tweetsCamley's Cartoon: Trump under fire over 'go home' tweets

At the Capitol, there was near unanimous condemnation from Democrats and a rumble of discontent from a subset of Republicans but notably not from the party's congressional leaders.

Nancy Pelosi, the House Speaker, who said Mr Trump's campaign slogan truly meant he wanted to "make America white again," announced the House would vote on a resolution condemning his new comments.

The resolution "strongly condemns" Mr Trump's "racist comments" and says they "have legitimised and increased fear and hatred of new Americans and people of colour".

In response, Mr Trump reverted to Twitter, saying: “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. Sad!"

But Republican Senator Mitt Romney, the party's White House nominee in 2012 and now one of the President's most vocal Republican critics, said Mr Trump's comments were "destructive, demeaning, and disunifying".

At home, Labour MPs Yvette Cooper and Hilary Benn both signed an open letter from Hope Not Hate in solidarity with the four US congresswomen.

Ms Cooper tweeted a link to the open letter, saying: "I've just signed this open letter standing in international solidarity with the congresswomen facing Donald Trump's racist attacks. Please do too."

Mr Benn retweeted Ms Cooper's tweet, saying: "So have I. We have to call it out for what it is."

On Monday night during the final head-to-head hustings, Mr Johnson and Mr Hunt both criticised Mr Trump for his remarks but refused to condemn them as racist.