But Carter also confirmed there is a personal side to the backstory of the campaign video: he was especially motivated, he said, because of Romney's frequent attacks on the presidency of his grandfather, including the GOP candidate's comparisons to the "weak" foreign policy of Carter andBarack Obama
What motivated him at first was Romney's role at Bain Capital and the controversy over whether the GOP candidate as a businessman had invested in companies that outsourced jobs overseas.
Carter had focused, in particular, on Bain Capital's 1998 investment -- while Romney was still chief executive -- in Global Tech Appliances, a Chinese manufacturing company. Carter was listed as providing "research assistance" to a July 11 story about the investment by David Corn, Mother Jones' Washington bureau chief and an MSNBC contributor.
http://firstread.nbcnews.com/_news/2012/09/18/13938614-how-the-romney-video-leaked-for-carters-it-was-personal?lite