Name the most lead margin for republican joe kenney being 23%
CREATE TABLE "opinion_polling_for_the_united_states_gu" (
  "poll_source" text,
  "dates_administered" text,
  "democrat_john_lynch" text,
  "republican_joe_kenney" text,
  "lead_margin" real
);
SELECT MAX("lead_margin") FROM "opinion_polling_for_the_united_states_gu" WHERE "republican_joe_kenney"='23%';