"This is all a matter of time here," former Bill Clinton adviser James Carville said of the prospect of President Joe Biden (pictured) stepping aside.Kevin Dietsch via Getty ImagesJames Carville was one of the masterminds behind Bill Clinton's winning presidential campaign in 1992.The Democratic strategist said on Monday that it's "inevitable" that Biden drops out.Carville said the Democrats should hold a series of town halls to pick a new candidate.A former advisor to Bill Clinton doesn't think President Joe Biden will be on the ballot this November."I don't predict things.