CREATE TABLE table_36607 ("District" FLOAT, "Incumbent" TEXT, "Party" TEXT, "Elected" FLOAT, "Status" TEXT)

In which District(s) has a Democrat held office since 1998?
SELECT "District" FROM table_36607 WHERE "Party" = 'democrat' AND "Elected" > '1998'
SELECT "District" FROM "table_36607" WHERE "Elected" > '1998' AND "Party" = 'democrat'