David Cameron has been accused of "chickening out" of reforming Britain's drug laws by a former government adviser.
The Prime Minister once called for "alternative ways" to tackle drugs, and criticised politicians for "posturing with tough policies".
He also backed a report that called for moves towards legalising drugs.
But his stance has hardened since he became Tory leader, and last year he rejected calls for a royal commission to look at whether drugs could be legalised.
Professor David Nutt, who used to chair the Advisory Council on the Misuse of Drugs, told HuffPost UK this was down to "pressure from the old men in the party who told him he could not get elected if he was not hard on drugs."
"Absolutely nothing changed," Nutt, who last week announced a drug that could be an alternative to alcohol without the hangover, said.
"He was told Tories were hard on drugs."
As a member of the Home Affairs Select Committee, Cameron voted in favour of the United Nations looking at whether the drugs trade could be legalised and regulated.
And in 2005, The Independent reported him saying "Politicians attempt to appeal to the lowest common denominator by posturing with tough policies and calling for crackdown after crackdown.
"Drugs policy has been failing for decades."
"It was the kind of thing a sensible, intelligent man with an Oxford degree would come up with," said Nutt.
"But then he just chickened out.
It's a huge disappointment. Now he's just a traditional Tory."
Asked about the coalition's record on drugs policy, Nutt said there was "no reason" for herbal substance khat to be made illegal, and said temporary banning orders on some drugs could be damaging to research.
However, he said the Lib Dems were "great", saying they had "tried to moderate some of the worst excesses of the government" and that he was optimistic about the appointment of Norman Baker to the Home Office.
On Cameron's change of stance, Nutt added: "Maybe he would have got elected if he had shown some courage."
But Anthony Wells, associate director of YouGov, said that while on the face of it, the public were relatively open to the idea of decriminalising cannabis, they did not care deeply about the issue and could have been easily swayed by a media backlash.
According to recent polling, 47% would support decriminalisation or full legalisation of soft drugs, 45% would be opposed.
Wells said: "Political parties always run a mile from being seen as soft on drugs.
"I suspect the public would be shifted by the frothy media outrage on it."
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