Complex sentence: Prohibited from seeking a third term, Casey left office on January 17,1995 but contemplated a run for President to oppose Bill Clinton in the 1996 Democratic primaries; he declined due to failing health.
Split into simpler sentences: Prohibited from seeking a third term, Casey left office on January 17,1995. He contemplated a run for President to oppose Bill Clinton in the 1996 Democratic primaries, but declined due to failing health.