user: Question: What is Party, when Results is "Re-elected", when First Elected is greater than 1990, and when District is "Minnesota 4"?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Results']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['Minnesota 1', 'Gil Gutknecht', 'Republican', 1994.0, 'Lost re-election Democratic gain']
SQL:

assistant: SELECT "Party" FROM "Table" WHERE "Results" = 'Re-elected' AND "First elected" > 1990.0 AND "District" = 'Minnesota 4';