Legal drugs = More drug users = More taxpayer dependent degenerates = More Democrats.
Well, I don't quite agree with your analogy there--

When a deep red state like Alaska legalized marijuana, and several deep red bible belt counties in Colorado voted to legalize weed, it just threw a tank full of water on your analogy of Democrats are the only ones that want marijuana legalized.
The FACT is that most Americans want marijuana legalized.
62% of Americans favor legalizing marijuana
The only ones that don't want it legalized are the two biggest lobbyists in Washington D.C. that fight against it.
1.
Law enforcement who love the easy busts of marijuana, so they can prop up their budgets and continually a ask for more money to chase it.
2..
Big Pharma who knows that a plant you can grow out in your back yard could wipe out half of your medicine cabinet, and put a huuuuge dent into their profits.