The polls were all way off in 2008, too. Just ask President McCain......
McCain never led with independents. Obama had that edge in 2008 and he was whooping McCain in the early vote. That is reversed now. The only way the polls are correct is if Democrats turnout equal to 2008 or if GOP turnout in even lower levels than 2008. I don’t know anyone who believes either of those things. Also we have referendums on Gay marriage in states like MN and ME that should drive up the conservative share of turnout in those states.