Brochu ran as a candidate of the newly formed provincial wing of the Ralliement créditiste in 1970 and won, becoming the Member of the National Assembly for the district of Richmond.
Nonetheless, Brochu and most of his colleagues lost their bid for re-election in 1973.
Brochu joined a group of Créditiste dissidents called Parti présidentiel in 1974 and became its leader in 1975.
Brochu won back his seat to the legislature as a Union Nationale candidate.
After he retired from politics, Brochu worked as a translator and as an ordained minister.