Robert Draper, writing in the New York Times, asks that question.
He offers a answer, too, although the GOP likely wont take the required remedy:
Later that evening at a hotel bar, Anderson [a GOP pollster] pored over her notes. She seemed morbidly entranced, like a homicide detective gazing into a pool of freshly spilled blood. In the previous few days, the pollster interviewed Latino voters in San Diego and young entrepreneurs in Orlando.
The findings were virtually unanimous. No one could understand the G.O.P.’s hot-blooded opposition to gay marriage or its perceived affinity for invading foreign countries. Every group believed that the first place to cut spending was the defense budget. During the whiteboard drill, every focus group described Democrats as “open-minded” and Republicans as “rigid.”
The GOP needs a more libertarian message.
It’s that simple, and consequently, that hard.