CREATE TABLE table_25104 ("State  ( class ) " TEXT, "Vacator" TEXT, "Reason for change" TEXT, "Successor" TEXT, "Date of successors formal installation" TEXT)

Name the vacator for failure to elect
SELECT "Vacator" FROM table_25104 WHERE "Reason for change" = 'Failure to elect'
SELECT "Vacator" FROM "table_25104" WHERE "Reason for change" = 'Failure to elect'