Wolf was either math-challenged or just used to seeing through red-colored glasses. But somehow those numbers had to be closed down, and he had a temporary brain fart and mistakenly thought that to even it out he had to reveal that the CNN polling group they assembled was put together purposely with an 8% tilt to the Republicans side. (Even though a more honest representation selection would be a more Democratic leaning group if you were reading the polls).

I didn't actually watch it so maybe I'm wrong but based on your description, I think he let out a slip, he thought he had to but didn't.
It was CNN's backup plan if in fact Romney came out on top. Wolf could pull out this excuse on air in order appease the Democratic viewer (but their poll data would still go out as a win for Romney). Only he mistook how and when he was supposed to use that.

If Obama won, Wolf was probably supposed to just keep quiet about that 8%. CNN probably stacked it like that because they anticipated an Obama win and didn't want the numbers too far apart.

I think the MSM is sleazier than the politicians. They love the new ad revenue from the Citizens United ruling. They just have to keep it close.