Comes from the popular campaign bumper stickers "Obama '08" supporting the inevitable next president of the United States. Means to beat down a rival presidential hopeful's campaign in a simple and effective manner to a point where said candidate cannot return. Obamoating, Obamoated, Obamoates.
Person 1: Man, did you see Senator McCain's new ad trashing Senator Obama?
Person 2: Yeah, but Obama has already Obamoated the competition. That old McCain guy doesn't stand a chance.