I thought George H.W. Bush did that in 1989.
Yes, and the criteria are pretty arbitrary. If President Obama plans to enact any kind of gun control, then it will have to be similar to his expansion of reporting requirements to semi-auto rifles - by stretching out authority Congress has already delegated to him.
Assuming he wants to have that fight, the two places I see that are really open are importation of semi-automatic rifles, and perhaps implementing the proposed sporting purposes test for shotguns that they floated earlier in his term (which would turn a bunch of domestic shotguns into Destructive Devices under the NFA as well as ban a bunch of imported shotguns). I think either of those would be politically foolish though; but the Administration has done more than a few things I regarded as politically foolish.