On Wednesday the President of the United States retweeted three anti-Muslim videos from the account of Jayda Fransen, the deputy leader of Britain First.
The far-right group operates in the UK and in 2016 their leader, Paul Golding, campaigned for the London Mayoralty, losing to Sadiq Khan. The group's popularity has been on the wane in recent months but the President's retweets has given it a media boost.
The anti-Muslim videos have not been verified as genuine. Britain First's primary area of campaigning is online, and the accuracy of their social media posts has been questioned in the past.
A spokesperson for Prime Minister Theresa May condemned the President's actions.
It is wrong for the President to have done this.
They also condemned Britain First for using "hateful narratives".
President Trump publicly reacted to the backlash on Twitter, telling the British Prime Minister:
Brendan Cox is the widower of murdered Labour MP Jo Cox. Her killer Thomas Mair, who shouted "Britain First" during the attack, was given a whole-life sentence in November 2016.
On Thursday Mr Cox took to Twitter in defence of the Conservative Prime Minister.
Hours before, in reaction to the President's sharing of the anti-Muslim videos, Cox accused Mr Trump of legitimising the far-right in the UK.