Anita Hill's allegations against then-Supreme Court nominee Clarence Thomas were explosive but lacked documentary evidence. The allegations against Herman Cain were reportedly investigated, meaning there could be a paper trail.
Rick Perry certainly has the money and the organization. But he hasn't made headway in the polls and is even struggling in the state he governs.
Allegations that Herman Cain acted inappropriately toward two female employees in the 1990s are just emerging, and the details could be key. But the allegations will test the Cain campaign.
Republican presidential hopeful Michele Bachmann is sinking in the polls. A prominent voice in the tea party movement says "It's time for Bachmann to go."