The left should worry about ALL turnout, with exception to the ‘12 POTUS race. The left has, already, won the race for ‘12 POTUS, unfortunately.
Your pessimism is completely unwarranted. If you’re having suicidal ideation, then see a shrink.
Obama will lose like Carter, IMHO. The GOP got sixty percent of the white vote in 2010. That was a first. There’s no reason to expect that number to decrease. His energy and environmental policies are killing him with working class whites. Blacks are not thrilled by de facto amnesty for illegal aliens, with whom they’ll have to compete for low skilled jobs, or Obama’s embrace of queer marriage. You underestimate the damage Obama is doing to the rat party.