CREATE TABLE table_56608 ("Congress" CLOB, "Bill number" CLOB, "Date introduced" CLOB, "Sponsor" CLOB, "# of cosponsors" FLOAT)

Who was the sponsor on April 22, 2004?
SELECT "Sponsor" FROM table_56608 WHERE "Date introduced" = 'april 22, 2004'
SELECT "Sponsor" FROM "table_56608" WHERE "Date introduced" = 'april 22, 2004'