Slowly but surely. This may be the best approach, ease into it as the older generation of people grow to old to vote. Keep it toned down to something that's legal to do, but restrict it a little so the nay-sayers don't spread fears of rampant stoner riots in the streets.
D.c. just decriminalized it as well. You can carry upwards of two ounces on your person and can grow up to 6 plants, as long as you don't sell them. Merica.
it has long baffled me why governments across the world gift criminal enterprise with the cash cow of illegal drugs, especially now that most of them are aware that booze and tobacco are worse than any of the illegal lot; it makes no sense...