"Quebecers have always been able to rely on the PQ throughout its history and I can assure you that will be the case once more," interim leader Stephane Bedard said Tuesday.
Bedard was speaking after he and most of his fellow PQ caucus members were sworn in at the legislature.
The PQ was reduced to just 30 seats in the April 7 election, far behind the Liberals' 70 and just eight more than Francois Legault's Coalition party.
The defeat prompted Pauline Marois to announce her resignation and led to Bedard being named interim leader.
The next provincial election will be held in October 2018, giving the PQ ample time to choose a new permanent leader.
"I am going to make sure that we have the internal debates we need to, that we emerge united and that we offer people another path, a different Quebec," Bedard said.
Bedard attributed the election defeat not to the party's record as a government for 18 months but to the lack of clarity on whether the party would have held a sovereignty referendum if it had been re-elected.
The swearing-in of 27 PQ members — Bedard said three of the 30 successful candidates could not make it for personal reasons — was followed by the swearing-in of the Coalition caucus.
Another notable absentee at the PQ ceremony was the Maple Leaf after the sovereigntist party requested its removal from the ornate Red Room.
Premier-designate Philippe Couillard will unveil his Liberal cabinet on Wednesday afternoon.