Via Politico:

A TOP CAIN ADVISER tells us the former candidate plans to endorse in the next few weeks — certainly this month, in order to affect the Iowa caucuses — and is most likely to go GINGRICH. They have a personal relationship that goes back to Gingrich’s days as Speaker, a much longer relationship than Cain has with any of the others. And they disagree on few issues. Cain can offer some Iowa organization and his power as a surrogate in the African-American community (including churches), a weakness for the GOP.