The Republicans will take 2-4 seats, depending on whether Obama gets re-elected. Given the huge amount of seats that the Democrats need to defend (23, compared to just 10 for the Republicans), the Democrats are almost certainly going to suffer a net loss even if Obama gets re-elected.
And how well did similar math work out for Democrats in 2010?
What? I don't know if you're being a hack, but the Democrats had more seats to defend, just like in 2012. (In 2010, the Democrats as 19 seats, and the Republicans only 18.)