Party leader Jeremy Corbyn will reportedly stand by his Labour MP Jared O'Mara, who quit the Commons equality committee over his online homophobic comments he made before he was elected.
The MP for Sheffield Hallam, who ousted former deputy prime minister Nick Clegg from his seat in the last election, was under fire for comments he made between 2002 and 2004.
He wrote on the Drowned in Music website that singer Michelle McManus only won Pop Idol "because she was fat" and said it would be funny if musician Jamie Cullum was "sodomised with his own piano".
He also said that gay men were "fudge packers" and that overweight people did not "deserve our respect".
After stepping down from the committee, O'Mara, 36, apologised and said he was "deeply ashamed" of his actions.
But The Times reported that his party leader is likely to back him.
A Labour source told the paper: "Jared apologised to the parliamentary Labour Party this evening and owned up to having previously been sexist and homophobic. His honesty, openness and commitment to tackling these issues was well received by colleagues."
The Labour leadership said the remarks were "horrendous" and "vile" but sources said he would not be suspended from the parliamentary party.
O'Mara's said he had been wrong to make the comments and that "I understand why they are offensive and deeply apologise for my use of such unacceptable language.
"I made the comments as a young man, at a particularly difficult time in my life, but that is no excuse."
LGBT Labour said: "Whilst we recognise that these comments were made some time ago, that doesn't excuse such ignorance and bigotry.
"We expect a full and public apology from Mr O'Mara and ask that he meets with members of the LGBT Labour committee in order to understand the inequality many LGBT people face."