2024 Toronto—St. Paul's federal by-election

Prior to the by-election, Toronto—St. Paul's was considered a safe Liberal seat in Midtown, Toronto.[8] It had been held by the Liberals since the 1993 federal election.[9] The Government of Canada announced measures to protect the by-election from foreign interference.[10]

The Conservative Party nominated Don Stewart on January 24. He works for the Canadian Investment Regulatory Organization.[11][12] Stewart campaigned on the main tenets of the Conservative Party platform under Pierre Poilievre, including crime and support for Israel.[13]

Running for the Liberal nomination was Leslie Church, former chief of staff to Chrystia Freeland.[14] She later received formal approval to run for Liberal nomination in Toronto—St. Paul's in April 2024.[15] She ran against Emma Richardson, a senior advisor with Global Affairs Canada’s United Nations division.[16] The Liberal nomination was held on May 1 with Church winning the nomination.[17][18] In 2020, Church agreed to an ethics screen for being married to lobbyist "Sheamus Murphy..(who is) registered to lobby the Liberal government in relation to several major sectors with active policy files, including broadcasting, energy and pharmaceutical companies that are working on a COVID-19 vaccine."[19]

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.[14][20][21] 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.[20][22]

The Rhinoceros Party announced that Sean Carson would be the candidate on January 13.[23]

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.[24] 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.[25]

On May 17, the Centrist Party announced Ali Mohiuddin as their candidate.[26]

On May 24, the Green Party announced that Christian Cullis, a constituent coordinator for Ward 11 city councillor Dianne Saxe, would be their candidate.[27] Emma Richardson, who previously lost the Liberal nomination, also sought the Green Party nomination.[28]

On May 28, the People's Party announced that Dennis Wilson would be their candidate.[29]

The Longest Ballot Committee, a political movement focused on electoral reform in opposition to first-past-the-post-voting, and supporting proportional representation,[30] targeted this by-election.[31] This yielded a record 84 candidates, breaking the previous record of 48 set in the Winnipeg South Centre by-election of June 19, 2023.[32] The resulting ballot papers were nearly a metre (yard) long, requiring temporary changes to the Elections Act due to their unprecedented size.[33] One candidate, Félix-Antoine Hamel received 0 votes in the election, and is believed to be the first candidate to receive 0 votes in an election in Canadian history. He could not vote for himself, as he did not live in the riding.[34]