We have become a nation in perpetual mourning. Something like 36 deaths a day last year. All the President needs to do is to consider these people, these citizens, "principal" figures of the US Government. If we truly are a government of the people this shouldn't be too much of a stretch.
The opening words of the Second Amendment are "A well regulated militia..." It is hard to characterize the current situation as well regulated. The right to bear arms should be preserved, but rights come with responsibility.