Complex sentence: Van de Kamp ran for the office in 1990, hoping to succeed Deukmejian a second time, but lost the Democratic primary election to Dianne Feinstein.
Split into simpler sentences: Van de Kamp ran for the office in 1990, hoping to succeed Deukmejian a second time. But Van de Kamp lost the Democratic primary election to Dianne Feinstein.