Complex sentence: He was elected as a Republican to the Fifty-ninth Congress (March 4,1905--March 3,1907) but was an unsuccessful candidate for reelection in 1906 to the Sixtieth Congress.
Split into simpler sentences: He was elected as a Republican to the Fifty-ninth Congress (March 4,1905--March 3,1907). Welborn was an unsuccessful candidate for reelection in 1906 to the Sixtieth Congress.