Who were the candidates in the district first elected in 1998 whose incumbent ended up being Paul Ryan?
CREATE TABLE "wisconsin" (
  "district" text,
  "incumbent" text,
  "party" text,
  "first_elected" real,
  "results" text,
  "candidates" text
);
SELECT "candidates" FROM "wisconsin" WHERE "first_elected"=1998 AND "incumbent"='Paul Ryan';