Perhaps.
Clinton pal Bobby Rush: I’m supporting Obama
http://www.suntimes.com/news/politics/231872,CST-NWS-obama27.article
Which came as a shock to many here in Chicago, given the fact that there is no love lost between Bobby Rush and Obama. Plenty of people plenty of candidates, but that doesn't create or denote a "mentor" status.
I'm not sure if you're still trying to argue that Bobby Rush is Obama's "mentor," but anyone familiar with Illinois politics would chuckle at that idea.