Political Sending Reputation

Ever wondered what the sending reputation was for your favorite presidential candidate?

Here's the IP addresses and Sender Score ranking for the last three mailings I've received from each of them. The Sender Score number was noted at the time I originally received the message.

Candidate	IP	Score
Barack Obama	69.25.74.173	80
Barack Obama	69.25.74.172	70
Barack Obama	69.25.74.186	70
John McCain	64.203.105.82	65
John McCain	64.203.98.31	55
John McCain	64.203.105.83	65

A higher Sender Score number is usually considered better. Looks like very generally speaking, Obama's sending reputation may be a bit higher than McCain's. Of particular concern to me is both candidates seem to be mailing from multiple IP addresses. Why is that? I hope it's not to avoid blocking.