Look at the two-month trend in the table I linked to. It's significant.
No, no, I understand what you're saying here, it's just that races are obviously won individually. The generics can only show an overall positive/negative attitude towards the party nationwide, but I'm just not much of a fan of those types of polls. They always tend to be a masturbatory fantasy for 'Rats, since they are more often than not, leading the GOP.