Backers of the potency measure announced Friday that they’re unable to raise enough money to advertise what would have been the most serious attempt yet to roll back Colorado’s 2012 legalization amendment. Attorney Frank McNulty, who represents the Healthy Colorado Coalition, the group behind the amendment, made the announcement that they will withdraw the controversial amendment. The measure was cleared for the ballot last month by the Colorado Supreme Court, but its supporters said they could not raise enough money to support it.