CREATE TABLE table_18636 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

what's the party with incumbent being william b. bankhead
SELECT "Party" FROM table_18636 WHERE "Incumbent" = 'William B. Bankhead'
SELECT "Party" FROM "table_18636" WHERE "Incumbent" = 'William B. Bankhead'