WASHINGTON — With his gun control proposals facing an uncertain future in Washington, President Barack Obama is turning attention to state legislatures in an effort to prod Congress into action.

Speaking at the Denver Police Academy on Wednesday, Obama urged federal lawmakers to follow Colorado’s lead in enacting measures to curb gun violence. Last month, the state joined New York in adopting new firearms restrictions, while legislators in Maryland and Connecticut are moving forward with limits on military-style assault rifles.

“Colorado has shown that practical progress is possible,” he said, surrounded by officers in uniform. “If we’re really going to tackle this problem seriously then we’ve got to get Congress to take the next step.”

The four states, all led by Democrats, are advancing measures favored by Obama in response to the Dec. 14 shooting at a Newtown, Conn., elementary school that killed 20 children and six adults. While the president made reducing gun violence a second-term priority, he and his Democratic allies so far haven’t been able to transform public horror over the Newtown massacre into action at the federal level.

“The political reality hasn’t really changed since Newtown,” said Laura Cutilletta, an attorney who follows state gun measures for the Law Center to Prevent Gun Violence. “The will is there, and the public certainly seems to have mobilized around this issue, but the politics that surround this issue — the gun lobby and the forces that are exerting pressure on both sides — in that respect, that is still as it was before.”

Since the shooting, the National Rifle Association, the nation’s biggest lobby for gun owners and manufacturers with $219 million in revenue, has used its influence with Congress to throw up hurdles to legislation.

The Senate will consider this month a package of gun legislation that includes expanded background checks, a measure to curb gun trafficking and one to increase federal grants for school safety upgrades.

That’s a scaled-back version of the Obama’s original proposals, which included a renewal of the ban on assault weapons and high-capacity ammunition magazines. Senate Majority Leader Harry Reid of Nevada converted those items to an amendment that stands no chance of survival.

The White House is pursuing a duel-track approach to advance new gun controls. Vice President Joe Biden, who spent 36 years in the Senate representing Delaware, has taken the lead in meeting lawmakers and advocates on both sides of the issue. He’s also been working at the state level, calling legislators in Colorado and making appearances in New York and Connecticut.

“The vice president knows these senators so he can speak the language of folks who need persuading on these issues,” said Mark Glaze, executive director of Mayors Against Illegal Guns, a pro-gun-control group led by New York City Mayor Michael Bloomberg. “The president has a different role.”

Bloomberg is the owner of Bloomberg LP, the parent of Bloomberg News.

Even as they push on the national and state level, Obama’s aides are pre-emptively blaming Republicans, who have a majority in the House and enough votes in the Senate to hold up legislation, for stymieing action.

“If they decide they’re going block it, they can do that,” White House senior adviser Dan Pfeiffer said at a Politico breakfast Wednesday. He also warned they would face “significant consequences” at the polls if they do so.

Even one of the main components of Obama’s plan with significant public support — expanded background checks for all gun buyers — is running into roadblocks. To win some Republican support, Democratic aides say they have may have to drop a requirement that licensed gun dealers maintain records of checks performed on behalf of private sellers.

To create the aura of momentum, Obama is highlighting states that have moved while Washington didn’t.

Colorado is a state with a deep-rooted hunting tradition. It also was the site of two of the biggest mass shootings in U.S. history: the massacre at Columbine High School massacre in 1999 and another in July when a gunman opened fire at an Aurora movie theater.

The Aurora shooting, in which 12 people were killed and 58 wounded, spurred passage of the law that Gov. John Hickenlooper signed last month limiting the capacity of ammunition magazines and expanding background checks for gun sales.

“Colorado is proving a model of what’s possible,” Obama said in Denver. “There doesn’t have to be a conflict between protecting our citizens and protecting our Second Amendment rights.”

Next week, the president plans to travel to Connecticut, where the state legislature came up with a bipartisan agreement on legislation to widen a state ban on assault weapons, limit magazine capacity to 10 bullets and require background checks for all weapons sales. The ban on assault-weapon sales would take effect the moment Gov. Dan Malloy signs the measure.

“This is a new and historic model for the country on an issue that has typically been the most controversial and divisive,” Senate Pro Tem Donald Williams, a Brooklyn, Conn., Democrat, said just before the chamber approved the measure sending it to the House.

Lawmakers in Maryland on Wednesday passed a ban on sales of assault-style weapons and high-capacity ammunition magazines, impose new licensing requirements on handgun buyers, and bar the mentally ill from possessing firearms.