Ginsburg is a liberal appointed by A Dim and Kennedy and Scalia are conservatives appointed by GOP presidents. The liberal justices retire when they are assured a liberal Dim president will appoint their successor (with the exception of Souter who was a lib appointed by Bush I)These are the 3 oldest justices.
Romney will appoint liberals to replace Scalia and Kennedy and possibly Ginsburg shifting the balance from 5-4 conservative to 6-3 liberal and that folks will be all she wrote..