An interesting analysis from Nate Silver at fivethirtyeight.com.
Back when I used to do high school debate, there were all sorts of esoteric arguments related to the notion of positive and negative rights. The distinction, to simplify the matter greatly, is that a positive right is something that permits you to act a certain way -- something granted to you -- whereas a negative right is a claim to noninterference -- something that precludes action from being taken against you, either by government or by other people. You'll most commonly hear the distinction in association with libertarianism, as libertarians tend to regard positive rights as impure manifestations of government fiat power, whereas negative rights exist intrinsically outside of government, which in turn has a duty to protect them.
I never found this framing terribly satisfying as a matter of moral philosophy -- there are too many things which fall somewhere in between the two poles. But as a political matter, the distinction is potentially quite interesting.
The relevant data:
And more info/analysis here:
http://www.fivethirtyeight.com/2009/06/how-to-get-63-of-americans-to-support.html