This would require some other binding governmental forum. How would you ever get 38 States, acting independantly of each other, the pass exactly the same legislation? Remember, if the legislation wasn't exactly the same, they would not be passing for the same legislation.
Proposing a change that would put Congress out of the picture in the States collective actions would fundamentally change our way of government. I doubt the change would be for the better (it would take, in effect, a new Constitutional convention)
I could imagine the state's attorneys general could coordinate such a thing. Hell, we have the internet. I think the idea that coordination has to occur from the top down is obsolete. Just look at state "right to carry laws." Quite a number of states have recipricol agreements between each other to recognize permits to carry concealed firearms issued by other pariticpating states. This coordination was acheived in spite of a hostile administration in Washington that was trying to make firearm laws more restrictive at the federal level.