DENVER — Colorado’s governor signed bills Wednesday that place new restrictions on firearms, signaling a change for Democrats who have traditionally shied away from gun control in a state with a pioneer tradition of gun ownership and self-reliance.

The legislation thrust Colorado into the national spotlight as a potential test of how far the country might be willing to go with new gun restrictions after the horror of mass killings at an Aurora movie theater and a Connecticut elementary school.

Democratic Gov. John Hickenlooper signed bills that require background checks for private and online gun sales and ban ammunition magazines that hold more than 15 rounds.

The debate in the Democratic-controlled Legislature was intense, and Republicans warned that voters would make Democrats pay. The bills failed to garner a single Republican vote.

The bills’ approval came exactly eight months after dozens of people were shot in Aurora, and a day after the executive director of the state Corrections Department, Tom Clements, was shot and killed at his home. Hickenlooper signed the legislation right after speaking with reporters about Clements’ slaying.

Hickenlooper said large-capacity magazines “have the potential to turn killers into killing machines.” He also said he realized some gun owners may be inconvenienced but that “the potential for damage seems to outweigh, significantly, the inconvenience that people would have,” he said.

The bills signal a historic change for Democrats in a state where owning a gun is as common as owning a car in some rural areas.

“He just slapped rural Colorado right in the face,” said Republican Sen. Brophy, who represents an eastern plains district. “They are overwhelmingly upset about this.”

Both bills take effect July 1. People who currently own larger-capacity magazines will be able to keep them.