In a White House announcement Wednesday, Obama -- flanked by Vice President Joe Biden and four children who wrote him letters supporting an overhaul of the nation's gun laws -- said Congress should reinstate the assault weapons ban that expired in 2004, limit magazines to 10 rounds and institute universal background checks on gun buyers.
"While there is no law or set of laws that can prevent every senseless act of violence completely, no piece of legislation that will prevent every tragedy, every act of evil, if there's even one thing we can do to reduce this violence, if there's even one life that can be saved, then we've got an obligation to try," Obama said.
The announcement came slightly more than a month after Adam Lanza took his mother's weapons, killed her, and then invaded Sandy Hook Elementary School in Newtown, Conn. -- killing 20 first graders and six school staff members before killing himself.
"In the month since 20 precious children and six brave adults were violently taken from us at Sandy Hook Elementary, more than 900 of our fellow Americans have reportedly died at the end of a gun -- 900 in the past month," Obama said. "And every day we wait the number will keep growing."
Immediately after the announcement, Obama signed 23 executive orders that he called "commonsense measures" to help police, mental health professionals and schools to take action to protect Americans. He noted, however, the "most important changes" require congressional action.
"Weapons designed for the theater of war have no place in a movie theater," Obama said, referring to the July 20, 2012, shooting at the midnight showing of the latest Batman movie in Aurora, Colo., that left 12 dead. "A majority of Americans agree with us on this. And, by the way, so did Ronald Reagan, one of the staunchest defenders of the Second Amendment, who wrote to Congress in 1994, urging them -- this is Ronald Reagan speaking -- urging them to listen to the American public and to the law enforcement community and support a ban on the further manufacture of military-style assault weapons."
Obama noted that a federal background check law has prevented "1.5 million of the wrong people from getting their hands on a gun," but he said enforcement of the law is difficult "when as many as 40 percent of all gun purchases are conducted without a background check. That's not safe. That's not smart. That's not fair to responsible gun buyers or sellers."
Obama said though the reforms make sense it doesn't mean they will be easy to implement.
"If it were, we'd already have universal background checks. The ban on assault weapons and high-capacity magazines never would have been allowed to expire. More of our fellow Americans might still be alive, celebrating birthdays and anniversaries and graduations," he said, predicting "pundits" will whip up opposition.
Obama urged Americans to contact their congressional representatives and ask them whether they support reforms and if they say no to ask why.
"The only way to change is if the American people demand it," Obama said.
"We don't live in isolation. We live in a society, a government for and by the people. We are responsible for each other. We have the right to worship freely and safely; that right was denied to Sikhs in Oak Creek, Wis. The right to assemble peacefully; that right was denied shoppers in Clackamas, Ore., and moviegoers in Aurora, Colo.
"That most fundamental set of rights to life, liberty and the pursuit of happiness, fundamental rights that were denied to college students at Virginia Tech and high school students at Columbine and elementary school students in Newtown; and kids on street corners in Chicago on too frequent basis to tolerate; and all the families who never imagined they'd lose a loved one to -- to a bullet, those rights are at stake. We're responsible. ... Let's do the right thing."
Biden, who headed a task force that presented proposals to Obama, said there has been a fundamental shift in American attitudes toward guns since the Sandy Hook carnage Dec. 14.
"I have never seen the nation's conscience so shaken," Biden said.
Obama called for the Centers for Disease Control and Prevention to research the causes of gun violence, saying, "We don't benefit from ignorance," and called on Congress to confirm a director of the Bureau of Alcohol, Tobacco, Firearms and Explosives, a job that has been vacant for six years.
Earlier Wednesday, the National Rifle Association released a video, calling Obama a hypocrite for accepting armed Secret Service protection for his two daughters in their school, while he opposes more armed guards in all schools.
"Are the president's kids more important than yours?" an announcer asks. "Then why is he skeptical about putting armed security in our schools when his kids are protected by armed guards at their school?"
White House press secretary Jay Carney called the NRA ad "repugnant and cowardly."
Celebrity Couples of 2014 [PHOTOS]