In 1953, he entered the senate, called by Prime Minister Louis Saint-Laurent.

At this election, Fournier was heading a new municipal party, the Ralliement du Grand Montréal (Greater Montreal Movement), which brought together Drapeau's opponents.

During his term as mayor, Fournier confined himself to representative functions and acted more as a spectator, mainly because Drapeau's Civic Action League still held a majority on city council.

Partly due to this, Drapeau, now running under the banner of the Civic Party of Montreal, defeated him in a 1960 rematch.

His administration was especially marked by the opening of the St. Lawrence Seaway, the Boulevard Métropolitain and the candidacy of Montréal for the 1967 World's Fair.