US President Barack Obama has called for public support for proposed background checks for all gun buyers in the United States.
Speaking before a crowd in Denver, Obama held up new gun control measures enacted in Colorado - the scene of two of the deadliest gun massacres in US history - as "a model of what's possible".
The president said that taking action to reduce gun violence does not have to infringe on Second Amendment rights.
"There doesn't have to be a conflict between protecting our citizens and protecting our Second Amendment rights," Obama told a cheering crowd in the Western state with a strong tradition of gun ownership and hunting.
Obama is aiming to revive stalled momentum in Congress for several gun control measures, including universal background checks for gun buyers, that he called for after a gunman killed 20 children and six adults at a Connecticut school in December.
The US Senate is set to debate the issue of gun control next week.
John Hickenlooper, the state's Democratic governor, signed into law legislation passed by Colorado legislators to require universal background checks for gun buyers and ban ammunition magazines with more than 15 rounds last month.
"I've come to Denver today in particular because Colorado is proving a model of what's possible," Obama said, adding that the state has shown that "practical progress" can be made.
"If you want to buy a gun, whether it's from a licensed dealer or a private seller, you should at least have to pass background check to show you're not a criminal or someone legally prohibited from buying one."
- Barack Obama
Obama met privately with law enforcement and elected officials as well as relatives of victims of two Colorado mass shootings: at a movie theatre last year in the Denver suburb of Aurora and at Columbine High School in 1999.
He devoted most of his speech at the Denver Police Academy to trying to build the case for expanding the existing background checks to cover all gun buyers.
Loopholes in the law have exempted many buyers from such checks.
"Nobody is talking about creating an entirely new system. We are simply talking about plugging holes, sealing a porous system that isn't working as well as it should," Obama said.
"If you want to buy a gun, whether it's from a licensed dealer or a private seller, you should at least have to pass a background check to show you're not a criminal or someone legally prohibited from buying one. And that's just common sense," Obama added.
No major gun legislation has passed the US Congress since 1994, but Obama has made gun control one of his top legislative priorities.
Opinion polls show strong support for background checks and other gun control proposals, but gun rights advocates
led by the National Rifle Association have lobbied fiercely against any new measures.
In Denver, Obama mentioned some of his other gun control proposals - reinstating the ban on assault weapons and cracking down on high-capacity ammunition clips - that already appear to have little chance of passing the Democratic-led Senate, let alone the Republican-controlled House of Representatives.
Obama met two representatives of hunters' groups in Colorado.
The president said he has received "stacks of letters" from gun owners who want gun violence stopped, and urged people on both sides of the gun debate to listen to each other and try to be more empathetic.
Obama plans to visit Connecticut next week to continue his push for action on reducing gun violence.
Senate legislators in Connecticut passed the toughest US law on owning military-style rifles Wednesday.
The assembly's senate voted 26 to 10 in favour of the law, which was drafted after bipartisan debate, the majority Democrats announced. The lower house was expected also to vote yes shortly after, with Governor Dannel Malloy planning a signing ceremony on Thursday.