He ran as an Action libérale nationale candidate in the district of Papineau in the 1935 provincial election and won.

He joined Maurice Duplessis's Union Nationale and was re-elected in the 1936, 1939, 1944, 1948, 1952, 1956, 1960 and 1962 elections.

He did not run for re-election in the 1966 election and was succeeded again by Roland Théorêt.

Lorrain was appointed to the Cabinet in 1944, serving as Minister of Public Works until 1960.

This article about a Member of the National Assembly of Quebec from the Union Nationale is a stub.