Conservatives will choose an interim leader in Ottawa on Nov. 5, following their party's demotion to opposition ranks in last Monday's election.

The Conservative Party will meet a day after prime minister-designate Justin Trudeau unveils his cabinet, CBC News has learned.

Defeated candidates will be invited to Ottawa, although they will not cast a vote for an interim Conservative leader.

Outgoing Prime Minister Stephen Harper will remain an MP as the party moves to select an interim leader and start the process of electing a new permanent leader.

Former foreign affairs minister Rob Nicholson announced on Monday that he will run for the interim leadership of the party.

"Many of you reached out to me in recent days asking that I seriously consider the role of interim leader. I want to say that I am honoured and humbled by this gesture of support," Nicholson said in a written statement on Monday.

"The fact that so many of you believe I can make a contribution in this regard has convinced me to put my name forward."

Nicholson's announcement comes after former veterans affairs minister Erin O'Toole announced his candidacy for the interim leadership.

"I really think we have to show that we're serious about rebuilding right from Day 1 and I think the interim can be part of that," said O'Toole on Monday.

O'Toole and Nicholson will face competition from former public works minister Diane Finley, who was the first to publicly express interest in being the party's caretaker until a permanent leader is chosen.

Former cabinet minister John Baird, who quit politics earlier this year, said he will not run for the Conservative leadership.

Calgary MP Michelle Rempel is also mulling a run.

A total of 99 Conservative MPs will return to Ottawa when Parliament is convened.

The party has already started a complete review of the 78-day election campaign.