Table schema:
CREATE TABLE table_name_10 (party VARCHAR, district VARCHAR, results VARCHAR, first_elected VARCHAR)

Question: What is Party, when Results is "Re-Elected", when First Elected is greater than 1990, and when District is "Minnesota 4"?
SQL: SELECT party FROM table_name_10 WHERE results = "re-elected" AND first_elected > 1990 AND district = "minnesota 4"