user: Question: What party did Robert P. Letcher represent?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Kentucky 1', 'David Trimble', 'Adams-Clay Republican', '1816', 'Re-elected', 'David Trimble (A)']
SQL:

assistant: SELECT "Party" FROM "Table" WHERE "Incumbent" = 'Robert P. Letcher';