CREATE TABLE table_5311 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" CLOB, "Result" CLOB)

What party was re-elected as an incumbent of robert p. Kennedy?
SELECT "Party" FROM table_5311 WHERE "Result" = 're-elected' AND "Incumbent" = 'robert p. kennedy'
SELECT "Party" FROM "table_5311" WHERE "Incumbent" = 'robert p. kennedy' AND "Result" = 're-elected'