user: Question: Who was the vacator when the reason for change was Failure to elect?
Columns: ['State (class)', 'Vacator', 'Reason for change', 'Successor', 'Date of successors formal installation']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Tennessee (2)', 'Vacant', 'Failure to elect', 'Spencer Jarnagin ( W )', 'Elected October 17, 1843']
SQL:

assistant: SELECT "Vacator" FROM "Table" WHERE "Reason for change" = 'Failure to elect';