MP Dawn Butler appeared to share a tweet describing Ms Badenoch as “a member of the black associate class of white supremacy”.
Ms Butler quickly deleted her retweet of a post by Nigerian-British author Nels Abbey, who responded to the prospect of Ms Badenoch becoming Tory leader by describing “Badenochism” as “white supremacy in black face”.
Home Secretary Yvette Cooper said she had not seen the post, but when she read extracts from it, she told LBC: “Obviously I strongly disagree with it.”
Ms Butler was heavily criticized by figures in the Conservative Party, with several calling for her to lose the Labor whip.
Ben Obez-Jecti, who was elected MP for Huntingdon in July, said Ms Butler was “not the only one in government who holds that view about Kemi”.
He said: “It will be a test to see if Keir Starmer removes the whip or effectively endorses Butler’s disgusting endorsement of this stain.”
The Home Secretary was pressed on why no action had been taken against Ms Butler.
She said: “As I said, I haven’t seen the post and I think these kinds of party-related questions are always for the whip.”
Asked if the words in the post contained ‘racist sentiment’, Ms Cooper said: ‘The words you have read are clearly appalling and I would strongly disagree with them.
“So, I haven’t seen the post. I don’t know the circumstances of this, but I think we should congratulate Kemi Badenoch on her election.
“I will continue to disagree with her on all sorts of issues, but I still congratulate her on her election.”
Sir Keir has previously suspended the mandate of Labor MPs in response to comments about senior black Conservative politicians.
In 2022, he expelled Rupa Hook from the party for describing then-chancellor Kwasi Kwarteng as “superficially” black. Ms Huq apologized and reinstated the whip six months later.
Other Labor figures, including Sir Keir and Foreign Secretary David Lammy, hailed Ms Badenoch’s election as the UK’s first black leader of a major party as a historic moment.
In later posts, Mr Abbey said his initial comments were “obviously satirical” and “intended as a sketch”, but defended Ms Butler, saying she “may not welcome the rise of a far-right reactionary black man’.
He added: “Because of things like these, which are bitter political disagreements, it is both fair and to be expected that many black people may not see Badenoch as (Opposition Leader) as a ‘proud moment for our nation’ in the the same way that, say, Keir Starmer does (or has the political mandate to do so).”