That is a dramatic collapse in GOP enthusiasm. Just take a moment to process that—less than half of Mitt Romney voters are very enthusiastic about their guy.
Of course, an unenthusiastic vote counts just as much as an enthusiastic one, so how much does it matter that they hate their guy? As the next question shows, there is a marked dropoff in voting intent between Obama and Romney supporters. This may not matter so much in the presidential contest given Obama's big lead, but it will be hugely important in a Senate race that remains deadlocked between Democrat Tim Kaine and Republican George "Macaca" Allen.
This intensity gap also gives us one of the first polls this cycle in which Obama's lead is bigger among likely voters (52-44) than registered voters (50-43).