Saying the Orlando killings could have erupted in "any one of our communities," Obama invoked previous mass shootings that jolted the nation.

"This massacre is therefore a further reminder of how easy it is for someone that lets them shoot people in a school, or in a house of worship, or in a movie theater or a night club," he said. "And we have to decide if that’s the kind of country that we want to be. To actively do nothing is a decision as well."

Obama's call for action, however, was much vaguer and more subdued than in addresses immediately following mass shootings earlier in his presidency.

The slaughter early Sunday at the crowded gay hangout is sure to stoke a new fight over restricting access to firearms even as new battles over LGBT rights, such as transgender bathroom equality and the “religious liberty” debate, play out in statehouses and City Halls across the country.

The gunman, identified by federal law enforcement as Omar Mateen, stormed the Pulse club wielding a handgun and an AR-15-type assault rifle, killing 50 and injuring another 53. Investigators were searching whether Mateen, who was found dead at the club, had ties to terrorist organizations.

After a gunman slaughtered more than a dozen elementary school children in Connecticut in 2012, Obama vowed to 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." Congress has actively stymied Obama's efforts to pass gun control legislation, including attempts by Democrats to force votes on legislation that would block people on the terror watch list from obtaining firearms.

Obama in January unveiled executive actions aimed at curtailing gun violence, including narrowing the so-called gun show loophole, and he has slammed the National Rifle Association for pressuring lawmakers to vote against any legislation altering the status quo.

"Each time this comes up, we are fed the excuse that common-sense reforms like background checks might not have stopped the last massacre, or the one before that, or the one before that, so why bother trying," Obama said in January. "I reject that thinking."

Both issues are also expected to figure prominently in the November presidential race.

Presumptive Republican nominee Donald Trump, who has also vowed to temporarily close the U.S. border to Muslim immigrants, said on Twitter the attacks prove he was “right on radical Islamic terrorism” and called for increased “toughness and vigilance.”

And Hillary Clinton, the likely Democratic nominee, said the U.S. needs to harden its defenses to “redouble our efforts to defend our country from threats at home and abroad.”