I don't know what the NRA's (or Republican party's) position is. I'm simply stating first a fact (People convicted of felonies are already prohibited from owning firearms) and a logical point (we'll need a clear an objective definition that can used to to objective prevent people from owning firearms). If you're willing to define what "mentally ill" is in a way that can be legally defined and structured for denying gun ownership, then we can have a starting point for discussing that point. Until then it's just a hand wave to say the mentally ill shouldn't own guns. I mean, seriously, how do we actually DO that? Have everyone in the country tested and put into a database with their mental health rating?