http://www.theatlantic.com/politics/archive/2014/03/the-republican-partys-pot-dilemma/284289/

In recent years, American public opinion has shifted rapidly in favor of legalizing marijuana. The percentage of adults who support it has gone from 12 percent in 1969 to 58 percent as of last fall, according to Gallup; in the past decade alone, support for legalization has increased by 24 percentage points. The shift has powered a wave of political victories for marijuana advocates, from the 20 states where medical marijuana is now legal to the unprecedented ballot measures legalizing the drug in Colorado and Washington in 2012. Three more states expect to put pot to a popular vote this year, with referenda on medical marijuana in Florida and full legalization in Oregon and Alaska.

What opposition remains is concentrated among Republicans. According to Gallup, only about a third of Democrats and independents now oppose legalization, compared to nearly two-thirds of Republicans. Opponents of legalization are also disproportionately elderly. The situation closely parallels the party's predicament on gay marriage, which most Republicans still oppose even as widening majorities of the broader public support it.

It adds up to a quandary for the GOP: Should it embrace the unpopular position still disproportionately favored by its members and risk marginalization as a result? Or will the burgeoning conservative voices in favor of legalization win out? Simply put, do Republicans want to be on the losing side of yet another culture war?

...The tide, (Beach, producer for Morning in America) believes, could still turn back against legalization—if the opponents' dark predictions come true and states like Colorado and Washington experience serious consequences from their embrace of marijuana. "The beauty of America is that the states can experiment with this and we will see what happens," Beach said. "But I am afraid of the effects it's going to have on society."