DENVER — A casino-backed group has raised more than $6 million to promote a ballot proposal aimed at allowing Colorado casino towns to raise betting limits, extend gambling hours and add games.

Meanwhile Denver lawyer Jon Anderson has filed papers to form a committee to accept contributions to oppose Amendment 50. He does not have a dollar yet.

The proposed amendment would let Black Hawk, Cripple Creek and Central City hold their own elections on whether casinos in their towns can raise betting limits from $5 to $100, operate 24 hours a day, and add craps and roulette.

Today, half of the revenues from the state’s gambling tax goes into the state’s general fund, with the rest going to statewide historic preservation and to the casino towns.

Under Amendment 50, 78 percent of the new proceeds raised by changes in the law would go to state community colleges. Casino towns would get the rest.

Anderson said he has no moral objection to gambling and is not aligned with anyone yet to oppose Amendment 50. He said he might support a less drastic increase in stakes but that the costs would outweigh the benefits.

“If this passes, you are going to create an economic incentive for the gambling industry, the Indian tribes and the corporations putting casinos across the country to expand gaming across Colorado,” he said.

Colorado already has gambling, said Katy Atkinson, a spokeswoman for Coloradans for Community Colleges, which backs the proposal.

“This just means we are getting more money from it.”

Sen. Abel Tapia, D-Pueblo, has said the measure could generate about $5 million a year.