Complex sentence: In 1958, he defeated incumbent Republican Robert J. McIntosh to be elected as a Democrat to the 86th United States Congress and to the eight succeeding Congresses, serving from January 3,1959 to January 3,1977.
Split into simpler sentences: In 1958, he defeated incumbent Republican Robert J. McIntosh to be elected as a Democrat to the 86th United States Congress. He was subsequently re-elected to the eight succeeding Congresses, serving from January 3,1959 to January 3,1977.