GULFPORT, Miss. — Guns in bars. Guns in airports. Guns in day care centers and sports arenas. Conservative state lawmakers around the country are pressing to weaken an array of gun regulations, in some cases greatly expanding where owners can carry their weapons.

But the legislators are encountering stiff opposition from what has been a trusted ally: law enforcement.

In more than a dozen states with traditions of robust support for gun ownership rights, and where legislatures have moved to relax gun laws during the past year, the local police have become increasingly vocal in denouncing the measures. They say the new laws expose officers to greater danger and prevent them from doing their jobs effectively.

“We are a gun society and we recognize that, but we should be writing gun laws that make us safer,” said Leonard Papania, the police chief in Gulfport, who opposes part of a new state law that creates exceptions to the rules for concealed-carry permits. “Do you want every incident on your street to escalate to acts of gun violence?”