Phrase Finder explains that the expression means to, “Maintain a level of activity and enthusiasm for a project.” The American version was preceded by a British phase to “keep the ball up,” or to keep the ball in the air to keep a game active. The American version comes from the presidential election of 1840 that had a campaign song, “Good news and true, That swift the ball is rolling on, For Tippecanoe and Tyler too.” There is a strange explanation for the ball mentioned in the song. Ten-foot diameter balls were made of tin and leather and pushed from one campaign rally to the next. Supporters “…were invited to attend rallies and push the ball to the next town, chanting ‘keep the ball rolling’.” Maybe we could convince one of our current candidates to resurrect the practice, or maybe not?