Former Home Office Minister Bob Ainsworth said he wanted to “replace dealers with doctors” as he argued for radical reform of drug laws in the House of Commons.
Letting doctors provide prescriptions for drugs such as heroin and cocaine would destroy the market dealers depended on, he said.
But the Coventry MP was criticised by a range of people, including his party leader, Ed Miliband.
Mr Ainsworth (Lab Coventry North East) had the chance to set out his case as he led a Commons debate.
But he provoked a strong response before the debate began, after talking about his proposals in a radio interview.
It led to Mr Ainsworth’s views being disowned by Mr Miliband. A spokesman for the Labour leader said: “These are not the views of Ed Miliband, the Labour party or the wider British public.”
Speaking in the Commons, Mr Ainsworth said: “I am not advocating kiosks on the street corners where people can buy cocaine.
“I am a parent and a grandparent. I want to make my grandchildren safer.”
He added: “What I’m advocating is that we replace the dealer who has got a ready market with the addicts who are there putting money in his pocket, and who is therefore prepared to sell heroin to children to extend his market, I want to replace that dealer with a doctor.
“I want to get those people into clinics, I want to give them prescriptions and I want to take away that dealer’s market.”
He added: “Ten years ago, Portugal decriminalised small amounts of drugs.
“Portugal is still there, it’s fine, it saved a fortune. Its HIV rates have crashed through the floor and the sky has not fallen in.”
Party leaders had to talk tough when it came to drug laws, he said.
But he pointed out that David Cameron, when he was a back bench MP and member of the Home Affairs Select Committee, backed a report calling for a full debate on alternatives to drug prohibition.
“Our now Prime Minister believed in it, and I have to say that I believe he still does. He just knows it’s tremendously difficult for him to take this position.”
However, Mr Ainsworth condemned an unnamed Labour source who apparently criticised him in conversations with some national newspapers on condition of anonymity.
“If you want to say anything about me and my views, give us your name. Say it on the record. I will not get offended.”
The MP was also criticised by Staffordshire MP Andrew Griffiths (Con Burton and Uttoxeter), chair of the all-part Parliamentary group for the Misuse of Drugs and Alcohol.
He highlighted Mr Ainsworth’s admission that he would have liked of introduced reforms to drugs laws when he was a Home Office Minister, but had not been able to win the support of colleagues.
Mr Griffiths said: “No wonder drugs policy was such a mess under Labour when a Home Office Minister wanted to legalise heroin.
“Drugs cause crime and can devastate communities.”