Complex sentence: Marilyn Quayle was a strong force behind her husband's bid in the United States presidential election, 2000; his campaign ended early, before any primary votings, when establishment Republican backings all aligned behind George W. Bush.
Split into simpler sentences: Marilyn Quayle was a strong force behind her husband's bid in the United States presidential election, 2000. His campaign ended early, before any primary votings, when establishment Republican backings all aligned behind George W. Bush.