Mississauga—Lakeshore

The riding of Mississauga—Lakeshore was vacated on May 27, 2022 following the resignation of Liberal MP Sven Spengemann to accept a position with the United Nations.^[2] Spengemann had represented the riding since 2015, when he defeated Conservative incumbent Stella Ambler.

Running for the Liberals was former MPP Charles Sousa, who represented the area provincially from 2007 to 2018 and previously served in the provincial cabinets of Dalton McGuinty and Kathleen Wynne, including as Minister of Finance from 2013 to 2018.^[20][21][22] Alex Crombie, a former Queen's Park staffer and son of Mississauga mayor Bonnie Crombie, was seen as a potential candidate prior to Sousa's nomination.^[23]

Running for the Conservatives was Ron Chhinzer, a police officer.^[21] Michael Ras, who finished second to Spengemann in 2021, considered running for the nomination before declining.^[20]

The NDP nominated Julia Cole, who ran for the seat's provincial counterpart in the provincial election earlier in the year, while running for the Greens was Mary Kidnew, a past president of the Hillcrest Ratepayers Association.^[21][24]

Rhinoceros Party leader Sébastien CoRhino contested the by-election.^[25] As well, the Rhinoceros Party organized a protest against the Trudeau government's abandonment of electoral reform in 2017 by running thirty-two^{[citation needed]} independent candidates, breaking their own record for most candidates nominated in a single riding in Canada, previously set in the riding of Saint Boniface—Saint Vital in the 2021 Canadian federal election.^[26]

Winnipeg South Centre

The riding of Winnipeg South Centre was vacated on December 12, 2022 following the death of Liberal MP and former cabinet minister Jim Carr.^[3] Carr had represented the riding since 2015, when he defeated Conservative incumbent Joyce Bateman, and had been battling multiple myeloma and kidney failure since 2019. Carr also defeated Bateman in rematches in 2019 and 2021.

Running for the Liberals is Carr's son Ben Carr, an educator and former staffer to Mélanie Joly.^[29][30][31] Winnipeg city councillor Sherri Rollins briefly ran for the nomination before withdrawing and throwing her support behind Carr.^[32][33]

The Conservatives have nominated Damir Stipanovic, an air traffic controller and member of the Royal Canadian Air Force Reserve.^[31]

Running again after previously running in 2021 are NDP candidate Julia Riddell, a clinical psychologist, and Green candidate Doug Hemmerling, a local educator.^[31]

The Longest Ballot Committee chose Winnipeg South Centre as its target for this group of byelections; the group protests the first-past-the-post election method by registering large numbers of independents in one riding in an election or group of byelections.^[34]

Oxford

The riding of Oxford was vacated on January 28, 2023, following the resignation of Conservative MP Dave MacKenzie, who had held the seat since 2004.^[5]

Arpan Khanna, the party's national outreach chair and 2019 candidate in Brampton North^[36] defeated Woodstock city-county councillor Deb Tait, MacKenzie's daughter and former ministerial staffer Rick Roth for the Conservative nomination.^[37][38] Gerrit Van Dorland, executive assistant to Cypress Hills—Grasslands MP Jeremy Patzer was running for the nomination until he was disqualified by the Conservatives over a dispute about whether he disclosed information to the party.^[39] In February 2023, MacKenzie accused the party of supporting Khanna, which he argues is a violation of the party nomination rules based on the Conservative's code of conduct, during the race.^[40][41]

Running for the Liberals is local realtor, former educator, and past Woodstock mayoral candidate David Hilderley.^[42][43] Citing concerns with the Conservative nomination process, previous MP Dave MacKenzie endorsed Hilderley in April 2023.^[42]

Western University professor Cody Groat defeated Matthew Chambers, the party candidate for the riding in the 2019 and 2021 elections for the NDP nomination.^[44][45]

Portage—Lisgar

The riding of Portage—Lisgar was vacated on February 28, 2023, following the resignation of Conservative MP Candice Bergen.^[47][7] Bergen, a cabinet minister in the government of Stephen Harper and the interim leader of the Conservative Party and Leader of the Opposition from February to September 2022, had held the seat since 2008.

Bergen's former campaign manager Branden Leslie defeated Rejeanne Caron, the party's 2019 candidate in Saint Boniface—Saint Vital and 2021 candidate in Elmwood—Transcona; Winkler resident Don Cruickshank,^[48] Morden-Winkler MLA and former Progressive Conservative Party of Manitoba cabinet minister Cameron Friesen;^[49] and Lawrence Toet, the MP for Elmwood—Transcona from 2011 to 2015 for the Conservative nomination.^[6][50][51] Liz Reimer, a Progressive Conservative Party of Manitoba staffer and former assistant to Friesen, and Josh Okello were previously running for the nomination, however after Friesen announced his campaign they withdrew their bids in order to run for the Progressive Conservative nomination in Morden-Winkler.^[52][53][54]

Maxime Bernier, who is the former MP Beauce and the current leader of the People's Party of Canada, announced on May 12, 2023, that he would run for the seat.^[55][56][57]

The Liberals announced Kerry Smith as their candidate on May 13.^[58]

Notre-Dame-de-Grâce—Westmount

The riding of Notre-Dame-de-Grâce—Westmount was vacated on March 8, 2023, following the resignation of Liberal MP Marc Garneau.^[8] Garneau, previously the Minister of Transport and Minister of Foreign Affairs in the government of Justin Trudeau, had held the seat since 2008.

Running for the Liberals is Anna Gainey, former president of the party and daughter of former Montreal Canadiens General Manager Bob Gainey.^[60][61] Gainey won the Liberal nomination on May 15, 2023, defeating Fred Headon, vice president and general counsel of Air Canada, and 2021 La Pointe-de-l'Île candidate Jonas Fadeu.^[62][61]

Human rights activist and Green Party deputy leader Jonathan Pedneault was announced as the party's candidate on May 15, 2023.^[63]

Calgary Heritage

The riding of Calgary Heritage was vacated on December 31, 2022 following the October 20 announcement from Conservative MP Bob Benzen that he would resign his seat by the end of the year in order to return to the private sector. Benzen had held the seat since a 2017 by-election in which he was elected to replace former Prime Minister and former Conservative leader Stephen Harper.^[4][65] The by-election was called for July 24, 2023, following the conclusion of the 2023 Alberta general election.^[66]

Shuvaloy Majumdar, global director for Harper's international consulting firm Harper & Associates defeated former parliamentary staffer Quinn Heffron for the Conservative nomination.^[67][68][37] Elliot Weinstein was acclaimed as the candidate for the Liberal Party.^[69]

Durham

The riding of Durham, represented by former Conservative leader Erin O'Toole, was vacated on August 1, 2023 following his resignation and retirement from politics.^[71][9] O'Toole, who led the party from 2020 to 2022 and served as Minister of Veterans Affairs in the government of Stephen Harper, has held the seat since a 2012 by-election.

Jamil Jivani, conservative commentator and former president of the Canada Strong and Free Network, won the Conservative Party nomination, defeating Theresa Corless, a former Durham Catholic School Board chair.^[72]

Robert Rock, a Scugog township councillor, was acclaimed as the candidate for the Liberal Party.^[73] Rock previously sought the nomination for the Conservatives,^[74] but was not a contestant when the riding association chose its candidate.^[75]

The Rhinoceros Party announced its candidate on January 13.^[76]

On January 28, 2024, Prime Minister Trudeau announced that the by-election would be held on March 4, 2024.^[77]

Toronto—St. Paul's

The riding of Toronto—St. Paul's was vacated on January 16, 2024, following the resignation of Liberal MP Carolyn Bennett.^[10][79] Bennett, most recently the Minister of Mental Health and Addictions and Associate Minister of Health in the government of Justin Trudeau, had held the seat since 1997.

Running for the Liberal nomination is Leslie Church, former chief of staff to Chrystia Freeland.^[80] She later received formal approval to run for Liberal nomination in Toronto—St. Paul’s in April 2024.^[81] She will be running against Emma Richardson, a senior advisor with Global Affairs Canada’s United Nations division.^[82] The date for the Liberal nomination will be May 1.^[83]

Other prospective candidates for the Liberal nomination who declined to run, included former Toronto city councillor Josh Colle; former Ontario MPP Eric Hoskins, who represented the area provincially from 2009 to 2018 and previously served in the provincial cabinets of Dalton McGuinty and Kathleen Wynne, including as Minister of Health and Long-Term Care from 2014 to 2018; and Toronto city councillor Josh Matlow, who has represented the area municipally since 2010; Matlow ultimately decided not to run.^[80][84][85] With his riding set to merge with Scarborough Centre at the next election, Don Valley East MP Michael Coteau was seen as a potential candidate, in order to avoid a nomination battle with fellow Liberal MP Salma Zahid; Coteau ultimately declined to run.^[84][86]

The Rhinoceros Party announced that Sean Carson would be the candidate on January 13.^[76]

The Conservative Party nominated Don Stewart on January 24. He works for the Canadian Investment Regulatory Organization.^[87][88]

The NDP announced on April 17 that Amrit Parhar would be the candidate. She works as the Director of Programs at the Institute for Change Leaders, an organization that was founded by Toronto mayor, Olivia Chow.^[89] It was previously reported two days earlier by The Hill Times that MPP for Toronto—St. Paul's, Jill Andrew was considering seeking the nomination.^[90]

The Longest Ballot Committee has chosen the riding for its next target;^[91] this may result in dozens of independent candidates.

LaSalle—Émard—Verdun

The riding of LaSalle—Émard—Verdun was vacated on February 1, 2024, following the resignation of Liberal MP David Lametti.^[92] Lametti, who previously served as Minister of Justice and Attorney General in the government of Justin Trudeau, won the seat in 2015.

The candidates seeking the Liberal nomination are:

• Eddy Kara: Political strategist.^[93]
• Christopher Baenninger: Chairman of the Board for Social Business Creation at HEC Montreal and Quebec Liberal candidate for the 2023 Saint-Henri—Sainte-Anne provincial by-election.^[94]
• Lori Morrison: Electoral Division 1 Commissioner of the Lester B. Pearson School Board and small business owner.^[95]

On March 28, Craig Sauvé, independent city councillor for the district of Saint-Henri—Little-Burgundy—Pointe-Saint-Charles announced that he was standing for nomination for the New Democratic Party's candidate.^[96] He will be officially nominated as the candidate on April 28.^[97]

Gregory Yablunovsky will be the PPC candidate. He was previously the party's candidate in Saint-Laurent in 2021 and La Prairie in 2019.^[98]

Elmwood—Transcona

The riding of Elmwood—Transcona was vacated on March 31, 2024, following the resignation of NDP MP Daniel Blaikie.^[99]

Potential candidates for the Conservative nomination include Lawrence Toet, MP for Elmwood—Transcona, from 2011 to 2015.^[100]

Running for the NDP nomination is Leila Dance, the Executive Director for the Transcona Business Improvement Zone^[101] and Leilani Villarba, the Executive Director at Chalmers Neighbourhood Renewal.^[102]

Russ Wyatt, Winnipeg city councillor for Transcona, 2002 to 2018, and 2022 to present was pondering a run for either the NDP or the Conservatives. He said that he liked the NDP's domestic policies, but disliked their "woke nonsense," and he aligns with the Conservatives on international views and foreign policy.^[103] Ultimately, he decided not to run.^[104]