From the Pew Research Center:
While John McCain closed the gap in campaign news coverage last week, equaling the attention garnered by his opponent, Barack Obama remains the far more visible candidate in the eyes of the public. When asked which presidential candidate they have heard the most about in the news over the last week or so, 76% of the public names Barack Obama while just one-in-ten (11%) recalls John McCain.
But the Democratic candidate’s media dominance may not be working in his favor: Nearly half (48%) of the public says they have been hearing “too much” about Obama lately. And by a slight, but statistically significant margin – 22% to 16% – people say that recently they have a less rather than more favorable view of the putative Democratic nominee. Not surprisingly, a very large number of Republicans say they have heard too much about Obama lately. But 51% of independents share this opinion, as do as many as a third of Democrats.