Complex sentence: He entered politics with his upset victory in the 1957 general election as a candidate for the Co-operative Commonwealth Federation over Liberal Cabinet minister C.D. Howe, the "minister of everything" in the governments of William Lyon Mackenzie King and Louis St. Laurent.
Split into simpler sentences: He entered politics with his upset victory in the 1957 general election as a candidate for the Co-operative Commonwealth Federation (CCF). He won over Liberal Cabinet minister C.D. Howe, the "minister of everything" in the governments of William Lyon Mackenzie King and Louis St. Laurent.