MONTEVIDEO, Uruguay -- Uruguay's plan to create the world's first national, government-regulated marketplace for legal pot may be going up in smoke.

Delays in implementing the plan are putting it at risk as polls point to opposition gains in October general elections and show most Uruguayans oppose a legal pot marketplace. Opposition politicians have said they will seek to repeal or modify the legislation, which gives the national government power to oversee the production, sales and consumption of marijuana.

"I am convinced that the current project is never going to be applied," the principal opposition presidential candidate, Luis Lacalle Pou, told The Associated Press. "The entire project is not workable. The pharmacies don't want to sell the drug and nobody is going to register as a user, as the law obliges."

The legislation, which went into effect in May, allows for the growing of pot by licensed individuals, the formation of growers and users clubs, the sale by pharmacies of 40 grams of pot a month to registered users and the tracking of legally grown marijuana through a system of genetic markers of authorized plants.

President Jose Mujica and his Broad Front movement have promoted the plan as a way to deal with rising homicide and crime rates associated with drug trafficking and the increasing use of crack cocaine. In the last 13 years, the homicide rate in Uruguay has increased by 21 per cent and the rate of violent robbery by 250 per cent. Officials say a legal pot market could provide an alternative to crack and reduce the power of drug gangs.

"The appearance of drug trafficking signified a brutal cultural change in the world of crime and a nearly absolute disregard for the value of life," Mujica told The Associated Press in May. "So we decided to try to snatch away a part of that market."

But almost three months after the pot law went into effect, no legal marijuana has been planted and officials still have not held a competition to select growers. They also have given conflicting dates for when the drug might reach pharmacies, ranging from late this year to sometime in 2015.

Experts say delays are due to the fact no other country has attempted such a plan and that authorities still lack detailed plans and rules for creating the market. Disagreements within the government over basic aspects of the proposal are also holding things back.

Opposition Colorado Party presidential candidate Pedro Bordaberry said "the entire project is one big improvisation."

The man in charge of the program, Julio Calzada, has dismissed concerns, insisting the bids to select growers will be a success "and the project will go forward."

While Mujica's marijuana plan was widely applauded globally and seen as going beyond marijuana legislation in the U.S. states of Colorado and Washington, most Uruguayans oppose it. The most recent poll shows that only 27 per cent of Uruguayans questioned approved of the law and 64 per cent opposed it. Sixty-two per cent said they want the law repealed. The survey by the polling firm Cifra questioned 1,001 people between July 4 and 15, and had a margin for error of 3 percentage points.

"People are against drugs and don't distinguish between them," said Adriana Raga, director of Cifra. "For a small, educated sector -- very small -- marijuana is something special. But for the great majority of Uruguayans, all drugs are bad and marijuana is another bad drug, the same as base (cocaine) paste."

With elections nearing, politicians are paying heed to public opinion. The top opposition candidates are now supporting the repeal or modification of the law.

Polls show a tight race in October congressional and presidential elections between the Broad Front and the opposition. None of the seven presidential candidates appears capable of getting enough votes to win outright in the election's first round. That would set up a runoff on the last Sunday in November between the two top vote-getters.

For the law to be out of peril, the Ruling Front has to win both the presidency and a majority in congress, which it currently barely controls.

"The data that we now have does not show this is happening," said Raga of Cifra. "There are still three months of campaigning to go, but as of today it is not our hypothesis."

Uruguay's main polling companies say that between 39 per cent and 43 per cent of Uruguayans intend to vote for the leftist ruling coalition, which would need almost 50 per cent to keep its grip on the legislatures and assure that Uruguay's marijuana marketplace is implemented as is.

Lacalle Pou, who is second in the polls, has said he would try to repeal the articles of the law that allow for the sale of marijuana in pharmacies. Other factions in his conservative National Party want to overturn the law altogether.

Even the far-left Popular Unity coalition has said its legislators might oppose the legislation if they are elected.

"Commercialization (of marijuana) by the state is the wrong road to take," said Pablo Mieres, presidential candidate for the fourth-place Independent Party. "Decriminalization is a road that has to be taken on the international level. A country can't do it alone."