Keith Vaz could face an investigation by Commons sleaze watchdogs over claims he paid for male escorts.
The Labour MP has indicated that he will stand aside as chairman of the powerful Commons Home Affairs Committee after publicly apologising to his wife and children for the "hurt and distress" he caused them.
Mr Vaz, MP for Leicester East, who has two children, paid for two men to visit him at a flat he owns in London - as well as offering to pay for the party drug poppers, according to The Sunday Mirror.
He also allegedly offered to buy one of the men some cocaine when he was told that he liked to take the Class A drug during sex.
Asked about the scandal, Prime Minister Theresa May said people must be able to have "confidence" in their politicians.
She said: "What Keith does is for Keith and any decisions he wishes to make are for him."
Conservative MP Andrew Bridgen said he would write to the Parliamentary Commissioner for Standards regarding Mr Vaz's conduct.
Mr Vaz, 59, has temporarily stepped aside from the Home Affairs Committee, which has previously reviewed the UK's drug and prostitution laws.
Allegations include he paid for eastern European prostitutes, having unprotected sex, using the name "Jim" as an alias and asking that the "party get started".
Vaz issued a statement saying the allegations have been referred to his solictor.
He said: "I am genuinely sorry for the hurt and distress that has been caused by my actions, in particular to my wife and children.
"I will be informing the Committee on Tuesday of my intention to stand aside from chairing the sessions of the Committee with immediate effect."
In a separate statement, he accused the Mirror of paying the men involved, calling it "deeply troubling".
Labour leader Jeremy Corbyn indicated there was no need for Mr Vaz to stand down from the party, stating: "Well, he hasn't committed any crime that I know of. As far as I'm aware it is a private matter, and I will obviously be talking to Keith."
Labour leadership challenger Owen Smith declined to comment on the controversy surrounding Mr Vaz, who nominated him for the contest.