Table: election_results_1938_4
Columns: district
incumbent
party
first_elected
result
candidates

Question: Who are all the candidates when Sam Rayburn was incumbent?
SQL: SELECT "candidates" FROM election_results_1938_4 WHERE "incumbent" = 'Sam Rayburn'

Question: What was the party that was frist elected in 1919?
SQL: SELECT "party" FROM election_results_1938_4 WHERE "first_elected" = 1919