Because the lefties policies they've been screaming about for the last 8 years make nice talking points but in reality can't work. Obama will need to realize this and try to adjust them toward the middle. His supporters and party members will resist.
Of course they can't work. But that didn't stop Lenin/Stalin, Mao, Pol Pot and Big Kim, from killing millions upon millions trying to *make* them work. Obama is an ideologue, he won't give up the ideology that he's been steeped in, from his early college days, at least, easily, if at all.