Lord Sewel has been suspended by Labour and urged to resign from the House of Lords after he was filmed allegedly taking drugs with prostitutes.
Lord Sewel, who is yet to comment on the claims, has already quit as Lords deputy speaker and chairman of the Lords privileges and conduct committee.
He could also face a police inquiry over the Sun on Sunday’s footage.
Labour MP John Mann said the 69-year-old should resign from the Lords voluntarily before he was expelled.
But sources in the House of Lords say Lord Sewel – who was appointed as a Labour peer in 1996 but has sat as a crossbench (independent) peer since taking up his standards role – has indicated he does not intend to quit as a peer.
It comes as the Sun published further photographs of the peer in Monday’s newspaper, along with details of new footage in which he is said to make disparaging remarks about a number of other politicians.
The original footage released appeared to show Lord Sewel snorting powder from a woman’s breasts with a £5 note.
Lords Speaker Baroness D’Souza condemned his behaviour, saying it was “shocking and unacceptable” and the allegations would be referred to the House of Lords commissioner for standards and the Metropolitan Police.
Standards Commissioner Paul Kernaghan will gather evidence and the cross-party privileges and conduct committee will then decide on a punishment.
Mr Mann said: “He cannot possibly go in front of his own committee and expect a serious hearing.
“He is a disgrace. He should retire and resign immediately.
“A lifetime ban would be the committee’s only option. He needs to save them and himself further embarrassment and go now.”
The House of Lords (Suspension and Expulsion) Act 2015 – which received Royal Assent only in March and which Lord Sewel himself helped to introduce – allows peers to be barred from Parliament if they breach the code of conduct.
The code maintains that members must “always act on their personal honour”.