CREATE TABLE table_28882 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" TEXT, "Result" TEXT, "Candidates" TEXT)

What party did robert p. letcher represent?
SELECT "Party" FROM table_28882 WHERE "Incumbent" = 'Robert P. Letcher'
SELECT "Party" FROM "table_28882" WHERE "Incumbent" = 'Robert P. Letcher'