DENVER — Supporters of tougher restrictions on the oil and gas industry in Colorado said Wednesday they won’t appeal a ruling by the state’s top elections official that kept two proposed constitutional amendments off the November ballot.

The organizers said they would instead work to defeat another proposal that would make it harder for voters to change the state constitution.

Wednesday was the deadline for the sponsors, Yes for Health and Safety Over Fracking, to appeal last month’s decision by the Secretary of State’s Office that they hadn’t turned in enough valid signatures to get the oil and gas measures on the ballot.

One would have required new wells to be at least 2,500 feet from homes and schools, up from 1,000 feet currently. The other would have given local governments authority to restrict or ban energy development, a power now held almost exclusively by state regulators.

Tricia Olson of Yes for Health and Safety Over Fracking and other supporters of the oil and gas restrictions said they would focus on defeating a measure that will be on the ballot, called “Raise the Bar” by its sponsors.

It would require voter-approved constitutional amendments to pass by 55 percent, up from 50 percent now. It would also require signatures of 2 percent of the registered voters in each of the state’s 35 state Senate districts to put amendments on the ballot.

Also announcing their opposition to the “Raise the Bar” proposal Wednesday were the Bell Policy Center and Colorado Fiscal Institute, both think tanks; Conservation Colorado, which describes itself as the state’s largest conservation group; and New Era Colorado, active in engaging and registering young voters.

Among other arguments, the groups said the proposal would favor well-funded interests, such as the energy industry, in gathering signatures statewide and fighting grassroots ballot proposals because it would make the petition-gathering process more costly.

Colorado voters rejected similar proposals in 1996 and 2008.