Complex sentence: Democrat John Breaux chose not to run for re-election and Republican David Vitter won his seat, and in South Dakota, Republican John Thune defeated the incumbent Senate minority leader Tom Daschle, the first time since 1952 that a sitting Senate leader lost re-election.
Split into simpler sentences: Democrat John Breaux chose not to run for re-election and Republican David Vitter won his seat, and in South Dakota, Republican John Thune defeated the incumbent Senate minority leader Tom Daschle. This was the first time since 1952 that a sitting Senate leader lost re-election.