Washington (CNN) President Barack Obama is mounting a final-year push to make gun control part of his legacy despite Republican opposition and is expected to announce unilateral action early this week.

He will join CNN's Anderson Cooper Thursday for an exclusive one-hour live town hall on gun control at George Mason University in Fairfax, Virginia, in hopes of mounting a final pitch to the public.

It's an issue he has had zero success on so far in his presidency, despite his repeated, emotional appeals for change. Congress has remained a roadblock even in the face of widespread public support for Obama's past calls for universal background checks or bolstered mental health support, with near uniform opposition from Republicans and a split on the issue among Democrats.

Obama will sit down with Cooper at 8 p.m. ET for the event, titled "Guns in America." The event's timing coincides with the fifth anniversary, next Friday, of the shooting of former Rep. Gabrielle Giffords , D-Arizona, in a rampage that left six dead and 13 others wounded.

In addition to discussing gun issues with Cooper, Obama will also take questions from the audience on the issue.

JUST WATCHED CNN to host Obama town hall on guns in America Replay More Videos ... MUST WATCH CNN to host Obama town hall on guns in America 01:04

Obama has repeatedly expressed his frustration with Congress' inability to pass new gun laws, and has frequently spoken out about increased gun control in the wake of mass shootings.

Ahead of Thursday's town hall, Obama plans to meet Monday with Attorney General Loretta Lynch to discuss options for tougher gun restrictions. He is also expected to announce in the coming days a new executive action with the goal of expanding background checks on gun sales.

Plans for the action are not yet complete, and those familiar with the process warn that unforeseen circumstances could delay an announcement. But gun control advocates are expecting the new actions to be revealed next week, ahead of Obama's annual State of the Union address, set for January 12.

Gun control advocates and White House officials say the focus remains on the so-called "gun show loophole," which allows certain sellers of guns -- at gun shows and elsewhere -- to avoid conducting background checks before making sales.

Congress would still need to act in order to make background checks fully universal. But advocates and administration lawyers have struck upon a provision in the law that could allow for Obama to expand the background check requirement to additional sellers.

A spokeswoman for House Speaker Paul Ryan said the White House hasn't contacted them about potential new legislation yet.

"The administration has not communicated with us, and we have not been briefed. We will consider options once we have information, but what seems apparent is none of these ideas would have prevented the recent atrocities," said AshLee Strong, the Ryan spokeswoman. "Our focus should be on the consistent causes of these acts -- mental illnesses and terrorism -- rather than infringing on law-abiding Americans' constitutional rights."

JUST WATCHED New action expected to expand background checks Replay More Videos ... MUST WATCH New action expected to expand background checks 04:54

Gun control advocates are also anticipating that the administration will bolster regulations on the reporting of lost and stolen guns. Currently, the Bureau of Alcohol, Tobacco, Firearms and Explosives is only required to investigate a gun theft if 10 or more guns are stolen and one of them is used in a crime. The administration is expected to tighten those requirements by reducing the minimum number of guns stolen that would prompt an investigation, and potentially eliminating the requirement that one of the guns is used in a crime.

Obama foreshadowed his actions in his weekly address.

"Change, as always, is going to take all of us," Obama said in his address. "The gun lobby is loud and well organized in its defense of effortlessly available guns for anyone. The rest of us are going to have to be just as passionate and well organized in our defense of our kids. That's the work of citizenship -- to stand up and fight for the change that we seek."

Photos: Obama leads country through grief President Barack Obama condemned the slayings of three Louisiana law enforcement officers on Sunday, July 17, as he called on the nation to condemn violence against law enforcement. "We as a nation have to be loud and clear that nothing justifies violence against law enforcement," Obama said, speaking from the White House press briefing room. "Attacks on police are an attack on all of us and the rule of law that makes society possible." Hide Caption 1 of 16 Photos: Obama leads country through grief U.S. President Barack Obama speaks during an interfaith memorial service for the victims of the Dallas police shooting on Tuesday, July 12. Obama sought to unify the country during the somber memorial in Dallas for the five police officers slain in a sniper ambush during what had been a peaceful protest. The incident occurred amid a tragic week for the nation that saw Alton Sterling in Louisiana and Philando Castile in Minnesota killed during encounters with police. Hide Caption 2 of 16 Photos: Obama leads country through grief President Obama and Vice President Joe Biden place flowers at a memorial on Thursday, June 16, for the victims of the nightclub shooting in Orlando. At least 49 people were killed in the massacre, the deadliest mass shooting in U.S. history. Hide Caption 3 of 16 Photos: Obama leads country through grief Obama pauses on October 1 during a news conference about the mass shooting at Umpqua Community College in Oregon. Hide Caption 4 of 16 Photos: Obama leads country through grief Obama sings "Amazing Grace" during a service in June 2015 honoring the life of the Rev. Clementa Pinckney, a South Carolina lawmaker. Pinckney was one of nine people killed in a shooting at a church in Charleston, South Carolina. Hide Caption 5 of 16 Photos: Obama leads country through grief Obama and first lady Michelle Obama arrive for a memorial service in Fort Hood, Texas, in April 2014. Officials say Army Spc. Ivan Lopez took a .45-caliber handgun onto the military post, killing three people and injuring 16 before taking his own life. Hide Caption 6 of 16 Photos: Obama leads country through grief Obama pauses as he speaks in September 2013 about the shooting at the Washington Navy Yard, mourning what he called "yet another mass shooting" that took the life of American patriots. Hide Caption 7 of 16 Photos: Obama leads country through grief Obama tours a tornado-affected area in Moore, Oklahoma, in May 2013. A tornado that ripped through Moore hit 2,400 homes on a 17-mile path. Hide Caption 8 of 16 Photos: Obama leads country through grief Obama speaks at the Cathedral of the Holy Cross following the Boston Marathon bombings that killed three people and injured at least 264 in April 2013. Suspect Tamerlan Tsarnaev was killed during an encounter with police, and his brother, Dzhokhar Tsarnaev, was sentenced to death. Hide Caption 9 of 16 Photos: Obama leads country through grief Obama attends a memorial service at Baylor University in Waco, Texas, in April 2013. Fourteen people, nearly all first responders, died in an explosion at the West Fertilizer Co. Hide Caption 10 of 16 Photos: Obama leads country through grief In December 2012, 20-year-old Adam Lanza walked into Sandy Hook Elementary School in Newtown, Connecticut, and killed 20 children and six adults. At the memorial service, Obama said, "In the coming weeks, I will use whatever power this office holds to engage my fellow citizens -- from law enforcement to mental health professionals to parents and educators -- in an effort aimed at preventing more tragedies like this." Hide Caption 11 of 16 Photos: Obama leads country through grief Obama walks back to the Oval Office of the White House in July 2012. Obama cut short a campaign stop in Florida in the aftermath of the mass shooting at a movie theater in Aurora, Colorado. Twelve moviegoers were killed and 70 were injured by convicted shooter James E. Holmes. Hide Caption 12 of 16 Photos: Obama leads country through grief Obama speaks on the campus of Missouri Southern State University after a tornado ripped through Joplin, Missouri, in May 2011, killing 158 people. Hide Caption 13 of 16 Photos: Obama leads country through grief The President and first lady hold hands during a memorial service for the victims of a Tucson, Arizona, shooting. On January 8, 2011, Jared Lee Loughner shot six people and wounded 13 more, including then-Rep. Gabrielle Giffords. Hide Caption 14 of 16 Photos: Obama leads country through grief An explosion at the Upper Big Branch Mine in West Virginia killed 29 workers in April 2010. It was the worst U.S. mine disaster in 40 years. "All the hard work; all the hardship; all the time spent underground; it was all for their families. ... It was all in the hopes of something better," Obama said about the fallen workers. Hide Caption 15 of 16 Photos: Obama leads country through grief Thirteen people were shot and killed by Maj. Nidal Hasan at Fort Hood in November 2009. Speaking to an estimated 15,000 people at a memorial service, Obama called the act "incomprehensible" and vowed that justice would be done. Hide Caption 16 of 16

"We know that we can't stop every act of violence," Obama said. "But what if we tried to stop even one? What if Congress did something -- anything -- to protect our kids from gun violence?"

Obama's move comes as Republican presidential contenders threaten to undo any executive actions he takes on guns if they replace him in the Oval Office.

Donald Trump vowed Saturday in Mississippi to "unsign" anything Obama implements.

"There's an assault on the Second Amendment. You know Obama's going to do an executive order and really knock the hell out of it," Trump said.

JUST WATCHED Trump sets sites on Obama gun control plans Replay More Videos ... MUST WATCH Trump sets sites on Obama gun control plans 01:04

"You know, the system's supposed to be you get the Democrats, you get the Republicans, and you make deals. He can't do that. He can't do that," he said. "So he's going to sign another executive order having to do with the Second Amendment, having to do with guns. I will veto. I will unsign that so fast."

But he's not the only Republican 2016 candidate making such threats.

"All these executive orders he's gonna come out with tomorrow that are going to undermine our Second Amendment rights -- on my first day in office, they're gone," Florida Sen. Marco Rubio said at a campaign stop in New Hampshire on Sunday morning.

New Jersey Gov. Chris Christie said on "Fox News Sunday" that Obama "wants to act as if he is a king, as if he is a dictator."

"Fact is, if he wants to make changes to these laws, go to Congress and convince the Congress that they're necessary. But this is going to be another illegal executive action, which I'm sure will be rejected by the courts and when I become President will be stricken from executive action by executive action I'll take."

And former Florida Gov. Jeb Bush said on "Fox News Sunday" that Obama should take his case to Congress -- rather than imposing new measures himself.

"His first impulse always is to take rights away from law-abiding citizens, and it's wrong. And to use executive powers he doesn't have is a pattern that is quite dangerous," Bush said.

Carly Fiorina told CNN's Dana Bash on "State of the Union" that Obama "has been lawless in his use of executive orders.

"It is delusional, dangerous, not to mention unconstitutional, for Barack Obama and Hillary Clinton to continue talking about climate change and gun control in the wake of a Paris terrorist attack, in the wake of a San Bernardino terrorist attack, instead of how we can defeat ISIS," Fiorina said.

Still, Democrats have rallied to Obama's side.

Vermont Sen. Bernie Sanders said on "State of the Union" that Obama has little choice but to act alone to strengthen background checks to keep guns out of the hands of criminals and the mentally ill.

"I would prefer that we could have bipartisan support, but the truth is Republicans aren't interested in doing anything on gun safety," Sanders said.

Democratic front-runner Hillary Clinton said Sunday she's "especially concerned (about 2016) because I know what a Republican president would mean."

She argued a GOP president would repeal executive actions on Day 1, "including one that we expect (Obama) to make in the next weeks to try to do more to have background checks for more gun buyers by requiring more sellers to do them."