Going around to blogs and mass emailing people is really bad form. Don't get me wrong... it's flattering that you've visited my site, and think that I'd benefit from your campaign information (read propaganda). If I may provide some advice... sending a single email to a bunch of bloggers is fine. But then, at the end of your email, say something like:

If you'd like to receive more emails from our campaign, please reply to this email and let me know, and I'd be happy to include you.

Do not say this:

If you don't want to receive any more of these, please reply and I'll stop sending these.

It may seem like a minor difference, but the first is polite and more welcoming, while the second smells of spam. The first displays confidence that we'll want more information, while the second displays arrogance and says that you think we need this information whether we want it or not.

Lastly, if you do go for the second option, and someone replies back saying they don't want any more emails, then immediately remove them from your list. That means you Katie MacGuidwin of the Republican National Committee.