With just over four months until October's federal election, here's a look at the still-growing list of MPs who are not running again, or at least not for the parties that helped them get elected in 2015.

Liberals losing at least 18 incumbents

At least 18 MPs who were Liberals last summer won’t be running again for the party this fall. The best-known is Scott Brison, the MP for Kings-Hants in Nova Scotia, who quit his position as Treasury Secretary in January.

Brison was first elected as a Progressive Conservative in 1997 and went on to spend 22 years in Parliament. During his farewell remarks in the House of Commons, Brison said he was leaving with his head held high and in order to spend more time with his young family.

Andrew Leslie, who served as lieutenant-general of the Canadian Forces before winning the Ottawa seat of Orleans in 2015, has said he won't run again.

Scott Brison

Scott Brison on Monday, Oct. 15, 2018. (THE CANADIAN PRESS/Sean Kilpatrick)

Andrew Leslie, who served as lieutenant-general of the Canadian Forces before winning the Ottawa seat of Orleans in 2015, has said he won't run again.

Celina Caesar-Chavannes, the outspoken representative from the Ontario riding of Whitby, announced her departure in March.

Caesar-Chavannes was one of the first Liberals to publicly support Jody Wilson-Raybould after the Globe and Mail broke a story alleging the PMO pressured her when she was attorney general to intervene in the criminal prosecution of SNC-Lavalin. Caesar-Chavannes said her decision to leave is for "personal reasons."

Wilson-Raybould (Vancouver Granville) was kicked out of the Liberal caucus along with former cabinet minister Jane Philpott (Markham—Stouffville). Both women will be running again, but as independents.

Celina Caesar-Chavannes

Celina Caesar-Chavannes on Friday, May 25, 2018. (THE CANADIAN PRESS/Justin Tang)

Four Nova Scotia Liberals – Bill Casey (Cumberland– Colchester), Mark Eyking (Sydney—Victoria), Colin Fraser (West Nova) and Rodger Cuzner (Cape Breton–Canso) – have also said they’re calling it quits.

"I am not sad to go. I am just happy to have had the opportunity to be here," said Cuzner in his farewell speech in the House. 

New Brunswick Liberal MP T.J. Harvey (Tobique-Mactaquac) announced he will not run for re-election after one term in office, citing his "desire to return to work in the private sector."

Also not running are Ontario MPs Borys Wrzesniewskyj (Etobicoke Centre), John Oliver (Oakville), and Don Rusnak (Thunder Bay—Rainy River).

West Vancouver MP Pamela Goldsmith-Jones has also decided not to re-offer. In her farewell remarks in the House of Commons she said "it will not surprise members to know that I am deeply disturbed by the stultifying and soul-destroying House of Commons rules that stipulate that the House sit on Fridays every week, or until midnight, or all night long. This is not democratic. This is not even humane. We should all be here in the House of Commons as our best selves, energized, not sleep deprived; optimistic, not frustrated."

Pam Goldsmith-Jones in the House of Commons
Pam Goldsmith-Jones during Question Period in the House of Commons on Parliament Hill in Ottawa, on March 21, 2016. (Adrian Wyld / THE CANADIAN PRESS)

The Liberals have also lost Nicola Di Iorio (Saint-Leonard—Saint Michel), who resigned from his Quebec seat last month after a long absence, and Ontario's Raj Grewal (Brampton East), who said he was resigning after a gambling scandal but has decided to continue sitting as an Independent.

There are also Hunter Tootoo (Nunavut) and Darshan Kang (Calgary Skyview); both were elected as first-time Liberals in 2015 and were relegated to the Independent benches after dealing with cases of misconduct.

Meanwhile, Leona Alleslev (Aurora—Oak Ridges—Richmond Hill) crossed the floor from the Liberals to the Conservatives.

At least 15 Conservatives are moving on

At least 15 people who were Conservative MPs last summer won't run again for the party this fall.

Among the most high-profile veterans moving on are Ontario MPs Kellie Leitch (Simcoe-Grey) and Rob Nicholson (Niagara Falls).

Leitch served as Minister responsible for the Status of Women under Stephen Harper. She famously proposed a "values test" for new Canadians when she ran for the party leadership.

Nicholson held a number of cabinet roles under Harper, including Minister of Foreign Affairs, Minister of National Defence and Minister of Justice and Attorney General.

Kellie Leitch

Conservative MP Kellie Leitch at Rideau Hall in Ottawa, Monday, July 15, 2013. (Adrian Wyld / THE CANADIAN PRESS)

"Even with my challenging experience during and following the leadership campaign, I will continue to talk about issues that matter to Canadians, like the ones they talk about every day at the dinner table and at Tim Hortons. This country and the responsibility we have as Canadians to help others both here and abroad is too important to me not to," said Leitch in her final speech in the House. 

Tony Clement, who also served in cabinet under Harper, was kicked out of caucus last fall after a sexting scandal. He has said he will not run again as an independent in his riding of Parry Sound—Muskoka.

Larry Miller, from the Ontario riding of Bruce—Grey—Owen Sound, is leaving after 28 years.

MP Larry Miller

Larry Miller announces his retirement. (CTV Barrie / Roger Klein)

Also retiring from the Conservatives’ Ontario caucus are Guy Lauzon (Stormont—Dundas—South Glengarry), Bev Shipley (Lambton—Kent—Middlesex), Dave Van Kesteren (Chatham-Kent—Leamington), David Tilson (Dufferin—Caledon) and Alex Nuttall (Barrie—Springwater—Oro-Medonte).

The party is also losing Alberta MPs Jim Eglinski (Yellowhead) and David Anderson (Cypress Hills—Grasslands), Manitoba’s Robert Sopuck (Dauphin—Swan River—Neepawa) and B.C.’s Mark Warawa (Langley—Aldergrove).

Maxime Bernier (Beauce) left the Conservatives last year after narrowly losing the leadership to Andrew Scheer. He went on to start the People's Party of Canada. Fellow unsuccessful leadership candidate Brad Trost (Saskatoon-University) is not running again, after he lost the nomination race in his riding.

New Democrats have lost nearly one-third of caucus

So far, the New Democratic Party is facing the biggest loss. Fourteen NDP members have decided not to run again, which is nearly one third of their 44-member caucus.

Ousted party leader Tom Mulcair resigned his Quebec seat (Outremont) in 2018, and the Liberals picked it up in last month’s byelection.

Kennedy Stewart (Burnaby South) left his seat in the fall and became Mayor of Vancouver. Muclair’s successor as leader, Jagmeet Singh, helped the party keep the seat in the byelection last month.

Sheila Malcolmson left the B.C. seat of Nanaimo-Ladysmith in October, and was later elected to the provincial legislature.

At least three more NDP from B.C. have announced their retirements: Nathan Cullen (Skeena—Bulkey Valley), Murray Rankin (Victoria) and Fin Donnelly (Port Moody—Coquitlam).

"I like the idea of farewell. The last number of weeks and months have been quite a strange experience for me. It has been a bit like being at my own funeral, actually. People come up to me and talk about how they feel about me, good and bad, and I get to hear comments that I think we do not share with each other nearly often enough," said Cullen in his farewell speech in the Commons. "I do not want anyone to look back, but it has been so long I actually had a full head of hair when I got here. I will ask that no one google that."

Nathan CullenNathan Cullen on Tuesday, June 5, 2018. THE CANADIAN PRESS/Sean Kilpatrick

In addition to Mulcair, four more Quebec members are leaving: Romeo Saganash (Abitibi—Baie-James—Nunavik—Eeyou), Helene Laverdiere (Laurier—Sainte Marie), Anne Minh-Thu Quach (Salaberry—Suroit) and Marjolaine Boutin-Sweet (Hochelaga).

NDP MP Romeo Saganash

Romeo Saganash on Tuesday, Sept. 25, 2018. (THE CANADIAN PRESS/Sean Kilpatrick)

Linda Duncan, the NDP’s only member from Alberta (Edmonton Strathcona), is moving on after more than a decade.

"Among my fondest memories of an election win was dancing in a pub with the visiting Mexican soccer team, excited that a socialist had been elected for Alberta. As with my colleagues, I was the first NDP and the first woman elected in my riding, but I was also the first NDP elected in Alberta in 25 years, and then re-elected and re-elected again," said Duncan in her farewell speech.

Longtime Ontario MPs Irene Mathyssen (London—Fanshawe) and David Christopherson (Hamilton Centre) have also decided to give up their seats.

Former NDP MP Erin Weir has also decided not to run again. After being removed from the caucus over allegations of harassment he became the sole representative of the Co-operative Commonwealth Federation. He said he is not running again because Singh continues to block his candidacy.