Complex sentence: Smith returned to his business as a city council lobbyist and, in the 1990s, also worked as a senior backroom adviser to Liberal leader Jean Chrétien playing a leading role in the party's election campaigns.
Split into simpler sentences: Smith returned to his business as a city council lobbyist. In the 1990s, he worked as a senior backroom adviser to Liberal leader Jean Chrétien, playing a leading role in the party's election campaigns.