What party was the winning one in the elections in the California 30 district?
CREATE TABLE "table1_1341663_6" (
  "district" text,
  "incumbent" text,
  "party" text,
  "first_elected" real,
  "result" text,
  "candidates" text
);
SELECT "party" FROM "table1_1341663_6" WHERE "district"='California 30';