There are 13 places PPP has polled the Republican race in October or November where it also did a poll sometime between January and March. In those places Romney's net favorability has dropped by an average of 15 points over the course of the year.

On average Romney's favorability with primary voters was 54/25 in these 13 places at the begininng of the year. Now it's only 50/35. His problem is partially that his positives have gone down but more than that it's that as his name recognition has increased, most folks moving off the fence have gone into the negative column.