Backers of a proposed ballot measure that would have put a number of marijuana regulations in to the Colorado constitution, including strict potency limits, announced Friday they were withdrawing their effort to gather signatures and put the issue on the November ballot.

“We simply couldn’t go toe-to-toe with the marijuana moguls who committed tens of millions to defeat our common-sense controls on the sale of recreational marijuana,” Ali Pruitt, a supporter of the campaign called Healthy Colorado Coalition, said in a statement. “The marijuana industry built a wall of money between us and the November ballot that we simply couldn’t break through.”

According to the secretary of state’s campaign finance records, Colorado Health Research Council was one of two groups opposed to proposed initiative 139 and it had raised $248,000 as of June 27, mostly from Colorado marijuana-related companies. The second registered issue committee opposing the initiative had not reported raising or spending any money.

According to a press release from the group trying to put 139 on the ballot, opponents of the measure filed legal challenges to delay the signature-gathering process and then was able to “buy off signature gatherers to keep the initiative from moving forward.”

Calls to both Healthy Colorado Coalition and the Colorado Health Research Council were not immediately returned Friday.

The measure would have asked voters to put several restrictions on the recreational sale of marijuana. Some of the restrictions are already in state law.

The constitutional amendment would have required pot be sold in child-resistant packaging; require edible marijuana products be sold as individually packaged, single-serving products; and required warnings on packages that included potency and health risks.

But the biggest change for the industry would have been a potency limit.

Marijuana and pot-infused products couldn’t exceed 16 percent tetrahydrocannabinol, or THC.

In current state law there is no limit to how potent marijuana or marijuana infused products can be, although there is a designated serving size that is now 10 milligrams of THC per serving and 100 milligrams total for an individually wrapped product.

There is no limit on what percentage that can be of the product.

An reveler uses a selfie stick to take a photograph in front of the crowd gathered to take part in 4/20 marijuana celebration Monday, April 20, 2015, in Denver. A mass lighting marked the end of multiple days of festivities to mark the unofficial 4/20 marijuana holiday in Colorado. (AP Photo/David Zalubowski)

David Zalubowski

(The Gazette file)

An reveler uses a selfie stick to take a photograph in front of the crowd gathered to take part in 4/20 marijuana celebration Monday, April 20, 2015, in Denver. A mass lighting marked the end of multiple days of festivities to mark the unofficial 4/20 marijuana holiday in Colorado. (AP Photo/David Zalubowski)