Labour MP Keith Vaz is facing a six-month suspension from the Commons after "expressing willingness to purchase cocaine for another person".
The Commons Standards Committee (CSC) recommended the suspension after finding Mr Vaz in "very serious breach" of the Commons code of conduct.
The move could trigger a recall petition, which could result in a by-election in Mr Vaz's Leicester East constituency.
The CSC had been investigating the former Home Affairs Committee chair over an incident first reported in the Sunday Mirror in 2016.
The newspaper report appeared to show Mr Vaz talking about cocaine with two men alleged to be escorts.
In the course of the encounter - which was covertly audio-recorded by one of the men - Mr Vaz was said to have offered to buy illegal drugs for a third person to use.
The committee said his explanation that the men were there to discuss the redecoration of the flat and that he may have been given a "spiked drink" was "not believable and, indeed, ludicrous".
The long-standing MP did not fully assist with the CSC probe.
It said that by failing to co-operate fully with the Commons inquiry process, Mr Vaz had shown "disrespect for the House's standards system" and caused "significant damage" to the reputation and integrity of the Commons as a whole.
But MPs must vote on the suspension before it can be enforced.
The inquiry was subject to repeated delays due to two referrals to the Metropolitan Police - who on each occasion decided not to proceed with a criminal investigation - the 2017 general election and Mr Vaz's ill health.
It took place under two commissioners for parliamentary standards - Kathryn Hudson and her successor Kathryn Stone.
However, the committee said that if the MP had given a "candid and co-operative account" of the incident from the outset, it could have been concluded much earlier.
It said "much of the welter of documentation and procedural challenges which has emanated from Mr Vaz has been designed, in our opinion, to 'throw dust in the eyes' of the commissioner and the committee".
It added that although the core issues facing the inquiry were relatively simple, "Mr Vaz has done his best to complicate, obfuscate and confuse the inquiry through arguments of little merit and documentation of dubious relevance".
Newspaper reports from the time claimed the MP cheated on his wife Maria Fernandes with alleged male escorts, but said she would forgive him.
However she did admit to the Mail on Sunday at the time that she "would have liked to have taken all my crockery and broken it on his head" following the revelation.
A statement posted on Mr Vaz's website said: "Keith Vaz has been treated for a serious mental-health condition for the last three years as a result of the events of 27th August 2016.
"He has shared all the medical reports in confidence with the Committee.
"He has nothing further to say on this matter other than what was said in his oral and written statements to the Committee and to the Commissioner."
Conservative MP Andrew Bridgen, who complained about Mr Vaz to the Parliamentary Commissioner for Standards, said that "1148 days" after making the complaint it had been "upheld".
He tweeted: "His conduct during the enquiry shows he is not fit to represent anywhere in Parliament, Leicester deserves much better than this."