Complex sentence: He was a candidate for U.S. Senator in 1847 but subsequently withdrew; he moved to Washington, D.C., and served as commissioner of customs in the United States Treasury Department from 1853 to 1858.
Split into simpler sentences: He was a candidate for U.S. Senator in 1847 but subsequently withdrew. He moved to Washington, D.C., and served as commissioner of customs in the United States Treasury Department from 1853 to 1858.