CREATE TABLE table_684 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Results" TEXT, "Candidates" TEXT)

Tony P. Hall was the incumbent in the race between what two candidates?
SELECT "Candidates" FROM table_684 WHERE "Incumbent" = 'Tony P. Hall'
SELECT "Candidates" FROM "table_684" WHERE "Incumbent" = 'Tony P. Hall'