The Miami Herald | 04/27/2003 | Bob Graham's workdays
This one gives credit for where Graham, uh, 'borrowed' the idea:
"Graham had retained a hotshot Democratic consultant named Bob Squier to develop his television commercials. Squier immediately grasped the visual possibilities, noting that he had created the television ads in 1974 for Tom Harkin, a working-class congressional candidate from Iowa who had tried his hand at various jobs throughout the campaign. The publicity from the jobs -- reinforced by Squier's television ads from the work sites -- helped elect Harkin."
For the record: Graham is running for vice president.