Table: us_house_1928_elections_2
Columns: district
incumbent
party
first_elected
result
candidates

Question: How many of the first elected were listed when Hatton W. Sumners was incumbent and re-elected?
SQL: SELECT COUNT("first_elected") FROM us_house_1928_elections_2 WHERE "result" = 'Re-elected' AND "incumbent" = 'Hatton W. Sumners'