Lack of volunteer depth kept Gingrich and Santorum off the ballot. Using incompetent or poorly trained signature gatherers kept them off the ballot. Failure to collect a significant excess of signatures kept them off the ballot. Paul got on the ballot because he has been through enough to know he should get 15,000 signatures when 10,000 were required. Can’t jump in at the last minute and expect to get everything right especially in a hard state like VA.
I heard that Romney and Paul were not subject to the 10,000 signature rule, because they both supplied the correct number in 2008. Heard that on Fox News.
Bachmann, Cain and Perry would not have been on the ballot either.