From Wikipedia,
http://en.wikipedia.org/wiki/Caging_list

Republican caging (voter suppression)

Monica Goodling was the first to publicly admit to the use of "vote caging" in her written and oral testimony to the United States House Judiciary Committee on May 23, 2007, mentioning that Tim Griffin, who was appointed as interim United States Attorney for the Eastern District of Arkansas, would have allegations of vote caging arise if ever presented to be confirmed by the Senate to the office, and that the Deputy Attorney General Paul McNulty "failed to disclose that he had some knowledge of allegations that Tim Griffin had been involved in vote-caging during his work on the president's 2004 campaign."