The New Democratic Party experienced serious internal divisions in 1989 over the nature and extent of its support for the proposed Meech Lake Accord on constitutional reform.
The Montreal Island Citizens Union won a majority on council, and Tassé served as a backbench supporter of Gérald Tremblay administration.
Following this election, Tassé served on the city's task force dealing with bedbug infestations[13] and oversaw the establishment of an open-data portal for municipal information.
[15] Following Tremblay's resignation as mayor, city council voted to choose a replacement, and Tassé supported Michael Applebaum's successful bid for the position.
[20] Tassé speculated that he might contest the 2013 municipal election as part of a group of independents in Verdun,[21] but he ultimately supported Marcel Côté's bid for mayor and joined the Coalition Montréal party.
[22] Under this party's banner, he ran for borough mayor of Verdun and finished fourth against Jean-François Parenteau of Équipe Denis Coderre pour Montréal.