CREATE TABLE table_18231 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

Which party does Tom Luken belong to?
SELECT "Party" FROM table_18231 WHERE "Incumbent" = 'Tom Luken'
SELECT "Party" FROM "table_18231" WHERE "Incumbent" = 'Tom Luken'