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President Obama has been notably silent on the issue of gun control during his presidency, in spite of at least four major mass shootings during his term - Binghamton, N.Y. (2009); Fort Hood, Texas (2009); Tucson, Ariz. (2011) and now Aurora, Colo.

In his few public statements on guns, Obama has balanced support for Second Amendment rights while emphasizing enforcement of existing laws and a national background check system rather than new controls.

The president has not mentioned gun control in any of his State of the Union addresses, including the 2011 address just days after the Tucson shooting. Meanwhile, his administration has expanded gun rights in some areas, allowing possession in national parks and on Amtrak. He has also backed off a 2008 campaign pledge to push for permanent reinstatement of the expired assault weapons ban.

"The president believes we need to take common sense measures that protect the Second Amendment rights of Americans while ensuring that those who should not have guns under existing laws do not get them," White House press secretary Jay Carney told reporters today aboard Air Force One. "We're making progress in that regard in terms of improving the volume and quality of information on background checks but I have nothing additional on that for you."

Read More About The Colorado Shooting HERE

President Obama was widely praised for his empathetic response in the immediate aftermath of the shootings that have occurred on his watch. But gun control advocates have been frustrated with his continued reluctance to push any legislative measures, including a ban on assault weapons or high-capacity ammunition magazines, to help prevent future tragedies.

"We are outraged," said the Brady Campaign to Prevent Gun Violence's Dan Gross on the Aurora shooting. "We understand that President Obama has just spoken and so might Mitt Romney. As someone who has suffered the lasting impact of gun violence, and president of Brady, I can tell you that we don't want sympathy. We want action."

The Aurora shooting is the largest mass shooting in U.S. history with 71 people hit by bullets.

In spite of the violence, Obama has preferred to stake out a middle ground on guns, mirroring an approach he took during as a candidate during the 2008 campaign. At the time his positions were seen as a nod to the gun lobby and gun owners in key battleground states.

In an op-ed for the Arizona Daily Star two months after Tucson, Obama avoided calls for tighter controls, even though shooter Jared Lee Lougher passed checks and legally purchased his weapons.

"I'm willing to bet that responsible, law-abiding gun owners agree," Obama wrote, "that we should check someone's criminal record before he can check out at a gun seller; that an unbalanced man shouldn't be able to buy a gun so easily; that there's room for us to have reasonable laws that uphold liberty, ensure citizen safety and are fully compatible with a robust Second Amendment.

"That's why our focus right now should be on sound and effective steps that will actually keep those irresponsible, law-breaking few from getting their hands on a gun in the first place," he said.

On the campaign trail in 2008 at a stop in Pennsylvania, Obama assured gun owners, "I'm not going to take away your guns."

"The 2 nd Amendment is an individual right and it means something," he said at the time. "What I also believe is there's nothing wrong with some common sense, gun safety measures. For example, that we should have strong background checks to keep guns out of the hands of criminals, to keep them out of the hands of mentally disabled.

"The bottom line is this, If you've got a rifle, if you've got a shotgun, if you've got a gun in your house, I'm not taking it away," he said.

Candidate Obama did campaign on permanent reinstatement of the expired assault weapons ban, and Attorney General Eric Holder in 2009 indicated that the administration would lobby for a bill. But that never materialized and the White House has avoided talking about it.

The Brady Campaign in 2010 awarded Obama an "F" on gun control for his first year in office, citing "extraordinary silence and passivity."

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