Seven of the 10 Bloc Quebecois MPs are quitting the party over Martine Ouellet’s leadership style.
They made the announcement after a Bloc caucus meeting in Ottawa Wednesday morning.
The seven will sit as Independents.
WATCH: Bloc Québécois in crisis as 7 MPs resign from party, will sit as Independents
The departures are a crushing blow to a party that formed the official Opposition under Lucien Bouchard in 1993.
Gilles Duceppe then took over the reins of the party and led it in five consecutive elections in which it won at least half of the seats in Quebec.