Complex sentence: Thereafter, Leach regained his state House seat in the 1983 nonpartisan blanket primary but again relinquished the seat to run unsuccessfully for state treasurer in 1987 in a campaign won by future U.S. Senator Mary Landrieu of New Orleans.
Split into simpler sentences: Thereafter, Leach regained his state House seat in the 1983 nonpartisan blanket primary. Leach relinquished his House seat again, this time to run unsuccessfully for state treasurer in 1987 in a campaign won by future U.S. Senator Mary Landrieu of New Orleans.