DENVER (AP) - Colorado pot skeptics have been cleared to start work on the most sweeping effort yet to attack legalization of the drug.

A ballot measure cleared for petitioning Thursday by the Colorado Supreme Court would set new potency and packaging limits on recreational pot.

Pot would have to include warnings that marijuana carries a risk of "permanent loss of brain abilities."

The measure also includes a new potency limit, meaning that popular forms of marijuana such as vape pens and some edibles would be illegal.

Supporters of the measure say that marijuana sold today is too strong.

Marijuana industry attorneys say the measure would ban 80 percent of marijuana products currently sold.

The court's ruling clears supporters to start collecting about 98,000 signatures to put the question on ballots.