PHOENIX - Saying voters have seen enough, a veteran lawmaker wants to give them a chance to repeal the state's 2-year-old medical-marijuana program.

The proposal by Rep. John Kavanagh, R-Fountain Hills, would repeal the entirety of Proposition 203, approved in 2010. Kavanagh said the measure, which passed by just 4,340 votes out of nearly 1.7 million ballots statewide, has proved to be a failure.

Kavanagh likely could get the 16 votes in the Senate and 31 in the House he needs to put the issue back before voters. But he still could have an uphill fight at the ballot box despite the narrow margin of support in 2010.

The trend nationwide at the ballot box has been in the other direction. And voters in two states - Colorado and Washington - actually agreed last year to make possession of small amounts of the drug legal, even without a medical reason.

Kavanagh said he never was a fan of Proposition 203, which allows those with a doctor's recommendation to get a card from the state allowing them to obtain up to 2 1/2 ounces of marijuana every two weeks. But it was a recent story, first reported last week by Capitol Media Services, that got his attention.

"The revelation ... that one out of nine schoolchildren who smoke marijuana illegally acquire it from cardholders to me was the last straw," he said.

Kavanagh acknowledged that the report, prepared by the Arizona Criminal Justice Commission, was not confined to what percentage of high schoolers got their marijuana from cardholders.

It also revealed that about one in six said they got their alcohol from a parent or guardian, with about an equal number saying they got it from another family member. And close to 30 percent who used prescription drugs to get high - and not for medical reasons - said they obtained them from the home medicine cabinet.

Kavanagh said the state should do what it can to shut off the supply of marijuana wherever it can.

"Let's crack down on parents and people who provide the other substances to kids," he said. "Let's not simply add a third item and make it even more available to children."

Kavanagh said the fact that cardholders are selling or giving away some of their marijuana should not be a surprise. He pointed out that the amount of the drug people can obtain legally adds up to close to 4 pounds a year.

No one involved with the original ballot measure returned calls late Thursday.

While backers of the medical-marijuana initiative needed to gather about 150,000 valid signatures to put the issue on the 2010 ballot, Kavanagh's proposal has a much smaller hurdle: He needs the backing of just 31 representatives and 16 senators to put the question of repeal back before voters in 2014; it does not even require the signature of Gov. Jan Brewer.