CREATE TABLE "opinion_polling_for_the_united_states_gu" (
  "poll_source" text,
  "dates_administered" text,
  "democrat_jill_long_thompson" text,
  "republican_mitch_daniels" text,
  "lead_margin" real
);

Question: What is the lowest Lead Margin when Republican: Mitch Daniels was polling at 48%?
SQL: SELECT MIN("lead_margin") FROM "opinion_polling_for_the_united_states_gu" WHERE "republican_mitch_daniels"='48%';