Regional Presidential Primary and Caucus Act of 2007 - Divides the United States into four regions of specified states (including the District of Columbia) for holding presidential primaries in each presidential election year. Requires four successive presidential primaries in each such year, to be held during the period beginning on the first Tuesday of March, April, May, and June and ending on the sixth day following such Tuesday.
Directs the Election Assistance Commission to establish procedures for the conduct of a lottery by March 1, 2010, to select which of four regions will hold the first primary.
Sets forth a rule for subsequent election cycles.
Provides that, in the case where a state elects to select delegates to a political party's national presidential nominating convention through a caucus, the state shall hold a caucus during the period in which its region is scheduled to hold a primary.