Could marijuana ballot initiatives be the key to Democratic electoral victories? Joshua Green at The Atlantic seems to think so. Acting on a tip from an Obama official, I found a few Democratic consultants who have become convinced that ballot initiatives legalizing marijuana, like the one Californians will vote on in November, actually help Democrats in the same way that gay marriage bans were supposed to have helped Republicans. Scott Morgan at StoptheDrugWar sums it up nicely: When political pundits…