CHICAGO - Democrats, looking to reverse their fortunes after two straight White House defeats, met Saturday to hear competing proposals to revamp the election calendar used to choose a presidential nominee every four years. The three major proposals would focus on regional primaries. Two of those proposals would allow Iowa and New Hampshire to retain their leadoff roles in the candidate selection process. A third plan, offered by Michigan Democrats, would create a rotating series of six regional primaries. A different region would launch each presidential nominating season. That plan would allow single-state contests to begin the process, but those...