Britain's Prime Minister  Boris Johnson faced calls to dismiss a controversial adviser.
London CNN  — 

A recently hired adviser to British Prime Minister Boris Johnson has resigned, after backlash grew against his controversial past comments – notably for claims that black Americans have lower IQs than white Americans and that compulsory contraception could prevent the creation of a “permanent underclass.”

Andrew Sabisky, a self-described “superforecaster,” announced his resignation as a “contractor” on Twitter Monday, saying that he did not want the “media hysteria about my old stuff online” to be a distraction for Johnson’s government.

“I know this will disappoint a lot of ppl but I signed up to do real work, not be in the middle of a giant character assassination: if I can’t do the work properly there’s no point, & I have a lot of other things to do w/ my life,” he said in another tweet.

The 27-year-old was hired by Johnson’s most senior adviser, Dominic Cummings, who advertised earlier this year for “weirdos and misfits with odd skills” to work alongside him.

Critics of the appointment singled out past comments made by Sabisky in support of eugenics and giving children mind-enhancing drugs for their educational benefits. “From a societal perspective the benefits of giving everyone modafinil once a week are probably worth a dead kid once a year,” he said in a 2016 interview.

In a 2014 comment on Cummings’ website, Sabisky wrote: “One way to get around the problems of unplanned pregnancies creating a permanent underclass would be to legally enforce universal uptake of long-term contraception at the onset of puberty.”

“Vaccination laws give it a precedent, I would argue.”

In a post on another website in 2014, he also suggested that black Americans have a lower average IQ than their white counterparts.

At the daily briefing for UK political journalists on Monday, a government spokesman repeatedly refused to say whether Johnson shared Sabisky’s views on eugenics, the selective breeding of humans.

“The Prime Minister’s views on a range of subjects are well-publicized and documented,” the spokesman said, according to the PA Media news agency.

Monday was the first time Sabisky commented on his past writings since they were revealed by the UK’s Times newspaper on Saturday, save to retweet the Times article.

Johnson had faced calls from his own side to ditch Sabisky. “Cannot believe No 10 has refused to comment on Andrew Sabisky. I don’t know him from a bar of soap, but don’t think we’d get on,” wrote a Conservative MP, Caroline Noakes, on Twitter. “Must be no place in Government for the views he’s expressed,” she said.

Since Johnson entered Downing Street last summer, his opponents have been concerned at the influence Cummings would have over the government. Critics say that Cummings, widely considered to have been the mastermind behind the successful 2016 Brexit campaign, has a brutal political style and fear that he is willing to run over anyone who stands in the way of his radical political agenda. Former colleagues say that he is a “Grade-A political rottweiler” and that “everyone who is on the opposing side should be astonishingly frightened.”

Cummings has a developed a reputation for being a political outsider, interested in ideas that are not usually discussed in Westminster circles. Between the 2016 referendum and his appointment to Downing Street, Cummings wrote long blog posts on topics such as artificial intelligence and reforming entire political systems. Cummings’ status after Brexit meant that his website became widely read in the British political world.

Cummings placed the “Weirdos and misfits” advert on his personal blog, encouraging his readers to apply via a gmail account rather than an official government address.

Supporters of Cummings say that even if he knew of Sabisky’s previous comments, it’s unlikely it would reflect his own views. However, friends of Cummings say they were not surprised someone with these views would end up on his radar: “To Dom a lot of this stuff is a discussion point, or philosophical banter,” one friend told CNN.

Opposition lawmakers do not buy this argument. Chris Bryant, a Labour MP, worried prior to Sabisky’s resignation that the contractor had been “hired because of these views, not despite them.”

“The first steps towards a really right-right wing government which tramples on normal fundamentals of democracy often starts with baby steps.”