Complex sentence: Former Prime Minister Jean Chrétien represented Beauséjour for a short time in the early 1990s after he won the Liberal leadership and the existing MP stepped down to allow him to have a seat in the House of Commons.
Split into simpler sentences: Former Prime Minister Jean Chrétien represented Beauséjour for a short time in the early 1990s after he won the Liberal leadership. The sitting MP stepped down to allow him to have a seat in the House of Commons.