CRFB estimates that Obama and Paul are about comparable for the deficit in 2021. I've been getting email updates from CRFB for a while. It's a little more alarmist on the short-term deficit than I'd like, but it's a good group.
It's also not some kind of Democratic front group that's going to try to make Obama look good. If you don't believe me, go to their site and look at their list of directors.