Part of the lack of Federal push is because many individual states/industries have interests in it not happening.
And one thing about the way the US has things set up, the States often function as the laboratories for social experiments. That's why you get things like Colorado being the first to legalize weed and Texas attempting to soft-ban abortion.
...yes, and we had to fight a whole war about that.
I cannot think of politically backlash stronger than "and then we went into Civil war about that topic, with the victors of the war settling the matter".
What point are you intending to make? That individual states/industries do not have the political power to influence a discussion at the Federal level?
And because of that impending banning of slavery, the South decided to bolt, instead of wait for the westward expansion of non-slavery friendly states to be added to the government.
It is utterly absurd there is not more a push to legalize at the Federal level.