So says Dan Bartlett, former Bush White House Director of Communications:

That’s what I mean by influential. I mean, talk about a direct IV into the vein of your support. It’s a very efficient way to communicate. They regurgitate exactly and put up on their blogs what you said to them. It is something that we’ve cultivated and have really tried to put quite a bit of focus on.

The rightwing blogs are not happy about Bartlett’s quote.  The rest of us have known it for quite some time though.