Complex sentence: After serving four terms in the House of Representatives, he ran for the Senate in 1988, where he lost in the primary; and in 1990, where he was defeated by Democratic incumbent J. James Exon by a 59% -41% margin.
Split into simpler sentences: After serving four terms in the House of Representatives, he ran for the Senate in 1988, where he lost in the primary. He ran again in 1990, and was defeated by Democratic incumbent J. James Exon by a 59% -41% margin.