DENVER — All but 10 of Colorado’s 64 county sheriffs have signed onto a lawsuit aimed at blocking the Democratic gun control measures passed by the state legislature and signed into law by Gov. John Hickenlooper back in March.

The sheriffs held a Friday morning news conference to detail their federal challenge, which is being led by the Independence Institute and its in-house Second Amendment expert Dave Kopel.

In March when the bills became law, the Independence Institute promised a legal challenge, specifically to two new laws: one limiting the size of ammunition magazines and another law to expand gun background checks.

“You can have sensible gun control laws that actually do protect public safety without infringing on people’s rights. These ridiculous new statutes are not in that category,” Kopel told FOX31 Denver earlier this year.

The laws were passed earlier this year in response to mass shootings in Aurora and at a school in Connecticut. Not all sheriffs opposed the bills, but some were frequent visitors to the state Capitol in an effort to prevent the gun controls.

Many opponents blasted Colorado lawmakers for listening to New York City Mayor Michael Bloomberg, whose group, Mayors Against Illegal Guns, lobbied heavily in favor of the background checks and magazine limits legislation.

“These laws didn’t come from Colorado,” Kopel said. “These laws are written by the Michael Bloomberg lobby, cookie cutter things that are pushed all over the country and in Congress — terribly mis-written laws by people who know very little about firearms or firearms laws.”

On its website, the Independence Institute is asking supporters of the lawsuit for financial donations to help them move forward with the suit.

Late Thursday, Dave Hoover, a police detective whose nephew, A.J. Boik, was one of the 12 people killed in last summer’s Aurora theater shooting, released a statement blasting the lawsuit.

“As someone whose family has been affected by gun violence and worked in law enforcement for many years, it is disappointing to see the majority of Sheriffs in this state turn gun safety and the safety of families and citizens of this state into a political issue,” Hoover said.

“These laws are supported by a majority of Coloradans because they protect public safety while respecting responsible gun ownership. Let’s encourage the Sheriffs to focus on public safety and enforce the laws they have sworn to uphold, instead of playing politics.”

On Friday morning, Tom Sullivan, whose son, Alex was among the Aurora victims, also released a statement.

“As a parent who lost my son Alex at the Aurora theater shooting, I ask these people to put themselves in my place,” said Sullivan, who confronted Republican state lawmakers with a very similar plea during a forum earlier this week.

“Imagine going around to hospitals trying to find your son, only to hear that he’s been shot dead and is lying on the floor of the theater. And then having to tell that to his mom and his sister, that he went to a movie and never came home. I do not understand why these politicians are picking guns over people, and why they want to make easier for criminals to get guns and for other families to go through what we did.”

Jeff Gross says he was shot 6 times, almost 7 years ago by someone who was stalking and harassing him.

“This person was waiting for me in front of my house and shot me 6 times at point-blank range, right in front of my house.”

Gross was asked about gun legislation that passed through the 2013 State Legislature.

“Over time, more and more states will follow in a similar way, what Colorado has done;  I do feel like it is progress.”