From Fort Hood, Tex. and Tucson, Ariz., to Aurora, Colo. and Newtown, Conn., President Obama has addressed mass shootings more than a dozen times since he took office in 2008.
In that time, his comments on guns have evolved markedly, from "thoughts and prayers" offered in the wake of a 2009 shooting in Binghamton, N.Y., to expressions of healing, anger, and finally, calls for political action on gun control.
On Tuesday, Mr. Obama outlined a series of executive actions on guns, including expanding mandatory background checks, increasing enforcement of existing laws, devoting $500 million more in federal funds to treating mental illness, and funding more gun-safety technologies.
The president's remarks, delivered in an emotional news conference, strongly condemned congressional inaction on gun control. He stressed the importance of protecting the constitutional right of Americans to bear arms, but made comparisons to the rights to education and worship denied to victims of gun violence during his presidency.
Political observers say it is the culmination of Obama's evolution on guns, one that has ranged from resignation to determination to act with or without congressional support, a consequence of the numerous mass shootings the President has responded to.
"It’s pretty obvious that part of his stronger commitment to gun safety and gun issues has been all of the mass shootings we’ve seen during his time in office and Newtown really took it to a whole new level," says Natalie Davis, professor of political science at Birmingham-Southern College in Alabama. "As he prepares to leave the scene in a year, he wants to leave his mark."
In fact, Obama, who famously lamented in his 2008 campaign that working class voters in economically-challenged Midwestern towns "cling to guns or religion," hasn't actually changed views on guns, says Harry Wilson, a professor of public affairs at Roanoke College in Salem, Va.
"What has changed are his priorities and the political climate," says Professor Wilson, who adds that Obama was preoccupied with health care, the economy, and Iraq in his first two years in office. After that, the President was focused on getting reelected in 2012.
"Now, he can afford to be himself," says Wilson. "There is no doubt that he cares about the issue; I think he has always cared, but he wasn’t sure he could win."
The president's desire to take action against gun violence has not always been evident.
When a January 2011 shooting in Tucson, Ariz., gravely wounded Congresswoman Gabrielle Giffords and killed six others, President Obama didn't use the occasion to make a bold call for gun control. Instead, he cautioned against divisive political rhetoric.
"It’s important for us to pause for a moment and make sure that we’re talking with each other in a way that heals, not in a way that wounds," he said, to cheers from conservative commentators like Charles Krauthammer.
He struck a similar note after the shootings in Aurora, Colo., stressing the importance of remembering the victims.
That changed on Dec. 14, 2012, when 20 children and six adults were gunned down at Sandy Hook Elementary School in Newtown, Conn., a moment Obama later named as the worst day of his presidency.
"We can’t tolerate this anymore," he said during remarks in which tears fell from his eyes more than once. "These tragedies must end. And to end them, we must change."
He charged ahead with 23 executive actions on gun control including measures to tighten background checks and to introduce an assault weapons ban, measures that later failed in the Democratic-controlled Senate, provoking ire, and perhaps resignation, from the President.
"This was a pretty shameful day for Washington," Obama said in an appearance after the lost Senate vote in April 2013.
Following his legislative defeat, the shootings at the Navy Yard in Washington, and at a church in Charleston, S.C., were greeted with resignation, with The Washington Post saying "He essentially waved the white flag on gun control, admitting there's not a lot more he can do."
But when a shooting at a community college in Oregon struck, Obama turned the tables, asking Americans to petition their lawmakers to strengthen gun laws.
"I would ask the American people to think about how they can get our government to change these laws," he said.
Polls suggest Americans overwhelmingly support at least some of Obama's gun control proposals.
Some 85 percent of Americans – including large majorities of Democrats (88 percent) and Republicans (79 percent) – favor expanded background checks, according to an August 2015 Pew report.
Some 79 percent favor laws to prevent people with mental illness from purchasing guns, 70 percent back the creation of a federal database to track all gun sales, and 57 percent support a ban on assault-style weapons, all proposals Obama has aired.
Nonetheless, at the same time, Americans appear to be more concerned about protecting gun rights than before.
Since 1993, Pew has asked respondents what is more important, controlling gun ownership or protecting the rights of Americans to own guns. In 1993, 57 percent of respondents said it was more important to control gun ownership and 34 percent said it was more important to protect gun rights. As of 2015, 50 percent of Americans say it is more important to control gun ownership, while 47 percent say it is more important to protect the right of Americans to own guns.
Which is why Obama is realistic about his latest set of executive actions on guns.
"We know we can't stop every act of violence, every act of evil in the world – maybe we can stop one act," he said Tuesday afternoon. "We can't save everybody, but we can save some."