I am a conservative and would have supported the law because I honestly don't care if your right to sell a high capacity rifle to a convicted felon is infringed but it isn't a voting issue for me. Start to infringe on my right to own and protect my family and that changes. For you I would assume it is a voting issue. If Obama wanted to increase me level of involvemtn he should have spent more time showing me how it would make a differience and less time trying less try to work up his base.
The politician can safely ignore my view on this issue since ti is way down on my list but he can't ignore yours even if more people agree with me than with you.
Contrary to public perception, he only time that a background check is not done is in the case of a face-to-face private sale between 2 individuals. There is no other legal transaction of a firearm. You can't go online and buy a gun and have it shipped to your house, it is illegal. They are sent to a licensed dealer near you and you have to go pick it up, at which time a background check must be done for the transfer from the dealer to you. Most transactions at gun shows are from federally licensed dealers. Yes, there are some individuals walking around with a gun for sale, but if you set up a booth, you must perform the background check because you are conducting a business transaction, not a personal sale.
As for your comment about selling a firearm to a felon, it is already illegal for me to do so. It is a violation of law for a felon to possess the weapon, and it is already illegal for me to supply him with one, even if I don't know about the felony.