Which American Labor candidate ran against Democratic candidate Robert F. Wagner?
CREATE TABLE "1938_state_election_results" (
  "office" text,
  "democratic_ticket" text,
  "republican_ticket" text,
  "american_labor_ticket" text,
  "socialist_ticket" text
);
SELECT "american_labor_ticket" FROM "1938_state_election_results" WHERE "democratic_ticket"='robert f. wagner';