More than half of Colorado sheriffs have agreed to launch a legal challenge to the state’s recently passed gun restrictions.

Thirty-seven of the state’s 62 elected sheriffs are prepared to sue to overturn laws that now prohibit the sale of ammunition magazines holding more than 15 rounds and require background checks for all private gun sales, Weld County Sheriff John Cooke said Tuesday.

Cooke said he expects more sheriffs will sign on to the lawsuit, but other sheriffs said they oppose the effort.

The County Sheriffs of Colorado, which represents the state’s sheriffs, will not take part in the lawsuit.

“The Board of Directors made a decision this was not something that the association should join in,” said County Sheriffs’ executive director Chris Olson.

San Miguel County Sheriff Bill Masters said he doesn’t think the new laws will be effective, but he won’t join in the legal action. “I’m not going to sue anybody for anything. I understand the frustration but I wouldn’t do that.”

The public is screaming for officials to take action to cut down on gun violence, Masters said.

But the legislature should have followed a recommendation contained in a County Sheriffs of Colorado position paper that called for tabling all gun control bills for at least a year to allow study of the issue before making any decisions, Masters said.

Cooke said he didn’t know if the lawsuit would be filed in state or federal court, but he said it likely would be filed within the next few weeks.

Delta County Sheriff Fred McKee said the legal action is in its “infancy,” and it is not certain to be filed.

The proposed lawsuit would say the law violates the Constitution’s Second Amendment right to bear arms and the 14th Amendment, which bars states from abridging the “privileges and immunities” of citizens, Cooke said.

The lawsuit would be handled by lawyer Dave Kopel, research director of the Independence Institute, a conservative think-tank, and adjunct Professor of Advanced Constitutional Law at the University of Denver’s Sturm College of Law, Cooke said.

Kopel couldn’t be reached for comment.

Tom McGhee: 303-954-1671, tmcghee@denverpost.com or twitter.com/dpmcghee