Diamond and Silk: Who are the Donald Trump super-fans and why are they angry with Facebook?

As Facebook CEO Mark Zuckerberg prepared for his appearance before Congress this week, he is unlikely to have anticipated facing so many questions about Diamond and Silk.

The Silicon Valley giant - quizzed by members of the House Commerce Committee over his company's role in the Cambridge Analytica data scandal and the social network's vulnerability to exploitation - was asked repeatedly about the Republican commentators and accused of banning their videos for political ends.

"Why is Facebook censoring conservative bloggers such as Diamond and Silk? Facebook called them 'unsafe' to the community. That is ludicrous. They hold conservative views. That isn’t unsafe," said Representative Joe Barton, a Texas Republican, reading aloud a message from a constituent.

Mr Zuckerberg responded by explaining that, "in that specific case, our team made an enforcement error and we have already gotten in touch with them to reverse it".

Senator Ted Cruz followed up by suggesting that blocking the pair's posts contributed to "a pervasive pattern of political bias", an assertion Mr Zuckerberg refuted.

But who exactly are Diamond and Silk?

The answer, in short, is President Donald Trump's most prominent African-American cheerleaders, Fox News regulars and right-wing social media stars who describe themselves as the incumbent's "Most Outspoken & Loyal Supporters".

President Trump only follows 45 accounts on Twitter - Diamond and Silk's is one of them.

The sisters, whose real names are Lynnette Hardaway and Rochelle Richardson, hail from Raeford, North Carolina, the daughters of husband and wife Christian evangelists, and rose to prominence during the 2016 presidential election campaign.

Their "Ditch and Switch" rallying cry encouraged voters to follow their example and abandon the Democrats and Hillary Clinton in favour of Mr Trump, an important endorsement for a candidate who had done much to alienate black voters on the road with a string of insensitive remarks on race.

"You're living in poverty, your schools are no good, you have no jobs, 58 per cent of your youth is unemployed - what the hell do you have to lose?" he asked the crowd in a speech in Dimondale, Michigan, in August 2016.

Profiled by Rolling Stone a month later, Diamond and Silk batted away remarks such as "laziness is a trait in blacks", attributed to the president in the 1991 book Trumped!: The Inside Story of the Real Donald Trump by John R O'Donnell.

"That don't make him racist," they argued. "That's his opinion."

The pair were also relaxed about President Trump receiving support from former Ku Klux Klan Imperial Wizard David Duke and said they were "tired" of the National Association for the Advancement of Coloured People, saying the organisation "doesn't speak for all black people".

The sisters continue to use Facebook, as well as YouTube and Twitter, as a key campaigning tool in support of the Trump administration and now have over 1.4m followers

Their dispute with Mr Zuckerberg began when several of their videos were removed by the site on 7 September last year.

After pursuing the matter with Facebook, Diamond and Silk were finally told on 5 April that the reason for their posts being taken down was that their "content and brand has been determined unsafe to the community".

The pair responded furiously to the ruling, which gave them no right of appeal, outlining their disagreements on Twitter on 7 April by asking: "What is unsafe about two Blk-women supporting the @POTUS @realDonaldTrump?"

Fox News joined their cause, with the channel's most prominent anchor Sean Hannity assuring them on Twitter that "your content is always welcome" on his personal website.

Diamond and Silk yesterday appeared on the chat show Fox and Friends, a favourite of President Trump, and argued their case against Mr Zuckerberg and Facebook, suggesting he was turning the site into "a political playground for Democrats".

"If he was concerned about his platform being a place for all ideas then why would he put algorithms in place to censor some ideas?" they asked.

"We are not unsafe. We are not animals. We are two black chicks that's down with politics, that's patriotic, that loves our country, that loves our president and that love his agenda."

Never short of a soundbite, Diamond signed off: "If Mark Zuckerberg can't make this an even playing field, Facebook is going to be the face without the book and the book with no pages when we're done."

In his congressional hearing, Mr Zuckerberg apologised for the decision against Diamond and Silk and answered Senator Cruz by agreeing that the California tech sector was an "extremely left-leaning place" but rejected the suggestion that Facebook was engaged in censoring Republican voices or purging right-wing comment.

Republican representatives Marsha Blackburn, Steve Scalise, Billy Long and Richard Hudson all weighed in on the women's behalf, with Ms Blackburn declaring: "Let me tell you something right now, Diamond and Silk is not terrorism."

Mr Scalise wanted to know if anyone had been fired over the "enforcement error" - Mr Zuckerberg said he did not know - while Mr Long repeated the campaigners' own question: "What is unsafe about two black women supporting President Donald J Trump?"

Mr Hudson, from Diamond and Silk's home state, asked how Facebook determines what is or is not offensive or controversial.

"The question of what is hate speech versus what is legitimate political speech is something we get criticised both from the left and the right on, [regarding] what the definitions are that we have. It's nuanced," Mr Zuckerberg answered.

Facebook is likely to face further scrutiny over its handling of freedom of speech issues going forward while Diamond and Silk are expected to continue to gather a cult following, their profile raised considerably by this week's discussion on Capitol Hill.