The nation's police chiefs are calling for universal background checks for anyone trying to purchase a firearm, saying opinion polls consistently show that most Americans support such restrictions.

At a gathering in Chicago of the International Association of Chiefs of Police, the top cops agreed the checks will help keep guns from people who shouldn't carry them.

Acknowledging the power of the gun lobby and the reluctance of Congress to enact stricter gun laws, the police chiefs told a news conference they were not anti-gun but wanted to keep weapons out of the hands of people with criminal backgrounds.

Backing the effort is an alliance of organizations representing police chiefs and executives, such as the Major Cities Chiefs Association and groups representing women, Hispanic and African-American law enforcement executives and police chiefs, as well as campus law enforcement administrators.

"This is a no-brainer, this is the simplest thing in the world," Chicago Police Superintendent Garry McCarthy said. "It troubles me all the time."

McCarthy said he was passionate about the issue after four years on the job in Chicago, which has more shootings and killings than other big cities like New York and Los Angeles and where police seize illegal guns at a much higher rate.

The police leaders called for expansion of background checks to cover all gun purchases and for a stronger background check system to ensure all agencies share the same records including criminal and mental health backgrounds.

A Gallup poll released last week showed 55 percent of Americans preferred tighter regulations on gun sales, something the National Rifle Association generally opposes. Pro-gun groups say increased background checks for gun buyers could infringe on Second Amendment rights to keep and bear arms.

"We took on the tobacco industry years ago," McCarthy said. "We're not going to give up, it's the most obvious thing in the world what we have to do in this country. I have more faith in America."

Current rules on background checks apply to licensed dealers, but up to 40 percent of firearms sales involve private parties or gun shows and do not require checks, the chiefs said.

The call for such checks for all purchases and not just those from licensed gun dealers is not new. But in the past, law enforcement officials have included such a call as part of a wider effort that included calls for longer prison sentences for those convicted of gun crimes.

By narrowing their focus to background checks that polls indicate have overwhelming public support, the chiefs say they hope they can convince the public to push lawmakers for legislation that will reduce gun violence.

Federally licensed gun dealers are required to run background checks before they make a sale. Between 1994 and 2010, the FBI processed more than 118 million applications. About 2.1 million of those (1.8%) were denied based on federal law that prohibits those with a pending felony charge, domestic assault conviction or restraining order, unlawful immigration status, dishonorable discharge from the military, deemed mentally incompetent by a judge, or involuntarily institutionalized from purchasing a gun from a federally licensed dealer.

A July 2015 Pew Research poll of 2,002 adults found 85 percent of Americans favor expanded background checks.

According to the Centers for Disease Control and Prevention, there was a total of about 464,033 gun deaths between 1999 and 2013, some 45% of which were homicides and about 55% of which were suicides.

Al Jazeera and wire services