Charting the discussion of issues during the 2004 presidential campaign, the study found political blogs -- online opinion and information sites -- played a similar, but not greater role, as the mainstream media in "creating buzz" around the candidates' campaigns.

The study dispels the notion that blogs are replacing traditional media as the public's primary source of information, said Michael Cornfield, a senior research consultant at Pew.

"Bloggers follow buzz as much as they make it," said Cornfield. "Our research uncovered a complicated dynamic in which a hot topic of conversation could originate with the blogs or it could originate with the media or it could originate with the campaigns.

"We can say that if people still have that idea that the bloggers are the new fifth estate, that the bloggers are the new kingmakers, that's not the case."