Conservative MP Andrew Scheer is ready to join the race to replace former prime minister Stephen Harper.

The former Speaker of the House of Commons plans to file his paperwork and then launch his leadership bid at an event in Ottawa tomorrow, where his campaign manager says he will appear alongside a number of fellow Conservative MPs and senators who support his candidacy.

The Saskatchewan MP stepped down as Opposition House leader earlier this month to focus on his efforts to join the race.

Scheer will be the sixth official candidate vying to lead the party, following fellow MPs Maxime Bernier, Michael Chong, Tony Clement, Kellie Leitch and Deepak Obhrai.

Several others have declared an intent to run or otherwise expressed interest in the job, including former Harper cabinet ministers Lisa Raitt, Chris Alexander and Erin O'Toole.

Conservatives will elect their new leader next May 27.