Endorsements by current and former officeholders were prominently featured and extensively leveraged by contestants during the 2023 Ontario Liberal Party leadership contest. This is a list of such elected officeholders who provided endorsements to candidates or had their expression of support reported in the media.

Caucus endorsements As typical in leadership contests of the two main political parties in Canada and other countries with government based on the Westminster model, the public support of incumbent caucus members were the endorsements most prized by the contestants and most often cited by journalists and pundits.

The Ontario Liberals only expand their caucus by one seat at the end of the 2022 Ontario election to a total of eight. Its rank was briefly reduced to seven due to a resignation, but expanded to nine late July that year following two byelections. Of the seven caucus members that were in office when the contest started in earnest in early summer, two were contestants (Ted Hsu & Adil Shamji), two declared neutrality (John Fraser as interim leader, and Stephen Blais as co-chair of the contest debates and result event), leaving only three potential caucus endorsements up for grab.

The three contestants who were not sitting MPPs each laid claims to one of the three MPPs as they launched their campaigns in late May to early June: Erskine-Smith was backed by his local MPP Mary-Margaret McMahon, Naqvi had his neighboring MPP Lucille Collard as a campaign co-chair, and Crombie's campaign launch was headlined by Stephanie Bowman. The Liberals welcomed two new MPPs in July following by-elections intensely contested by the governing Conservatives. Erskine-Smith was boosted in late August by the endorsement of Karen McCrimmon, the former Kanata MP who retired in 2021 but re-entered the fray and wrestled the provincial seat from the Conservatives. Crombie seconded her second caucus endorsement in late September when Adil Shamji ended his own bid and joined her campaign (though he did not bring with him his three endorsers). Andrea Hazel, the new MPP for Scarborough who defeated a star candidate handpicked by the Conservative premier, announced her support for Naqvi in late October, as the contest entered its final month. Endorsements tallies

MPPs MPs Current Former Current FormerTotal available 9~160 78 ~240Bonnie Crombie 2 23 15 5Nathaniel Erskine-Smith 2 2 5 6 Ted Hsu 1 (self) 3 1 3 Yasir Naqvi 2 20 9 7

Diminished significance of endorsements With so few caucus endorsements up for grab, the endorsements of Ontario MPs and former MPPs were again seen as indicators of strength and momentum. However, with the party foregoing the convention as the final step of the contest, the significance of such endorsements demonstrably diminished compared to the two previous contests in the preceding decades in two main ways. Firstly, MPs and former MPPs no longer have an formalized outsized votes through entitlement as automatic ex officio delegates. Secondly, their ability to influence subsequent ballot choices was also severely reduced, as there was no longer a period of reflection and intense support jockeying after the first ballot. While certain local results were clearly attributable to specific impactful endorsements, unlike the two previous contests, the general distribution of such high-profile endorsements were not reflected in first ballot results in any meaningful way. While Naqvi was frontrunner Crombie's main rival on the competitions for such endorsements, Erskine-Smith beat him by four percentage point on first ballot and gave Crombie a serious run on final ballot.

Regional distribution While the Ontario Liberal Party abandoned the usage of delegated convention, it retained the fundamental premise of equal weighting of input among all electoral districts regardless of membership size or number of votes cast. Endorsement of individuals represented or had significant influence in regions the Liberals has not fared well in recent years (and thus had relatively small Liberal Party membership roll) were therefore seen as particularly valuable. The three main campaign all made concerted efforts in securing and highlighting such endorsements.

Endorsement lists Endorsements are grouped together by contestant. The list under each constestant could be sorted by types of endorser, by geographical regions, by names, or by the constituencies the endorsers represented. Endorsements were assigned to one of the following five regions basing on the region endorser represented or hailed from. The regional assignment are informal and included for ease of review. The "weight" of the region, calculated by number of electoral districts are also included for reference:

Titles or offices held listed are current as of the December 2, 2023 when the leadership contest results were announced. This list only includes individuals who held public elected offices, or individuals/entities of prominence sufficient for their expression of support to be reported by news media. Bonnie Crombie Endorser Constituency represented Other roles held, notes MPPs MPP Tor. Don Valley West 2022–present MPP Tor. Don Valley East 2022–present Former MPPs (Plus: Baker listed under MPs) ExMPP North Sudbury 1995–2014 Cabinet minister 2003–13 ExMPP Tor. Etobicoke Centre 2003–2014 Cabinet minister 2005–10 ExMPP Tor. Oriole 1985–97 Cabinet minister 1985–86, 87–90 ExMP CenThornhill 1997–2004federal minister 1999–2003 ExMPP East Ottawa West—Nepean 1987–97, 2010–18 Cabinet minister 2010–18 ExMPP Tor. Scarborough—Rouge River 1985–2005 Cabinet minister 1985–89Speaker 2003–05 ExMPP Cen Dipika Damerla Mississauga East—Cooksville 2011–18 Cabinet minister 2014–18 City Mississauga city councillor (Ward 7 Cooksville) 2018–present ExMPP Tor. Scarborough Centre 2003–18 Cabinet minister 2007–18 ExMPP SW Sarnia—Lambton 1999–2007 Cabinet minister 2006–07 ExMPP SW Dwight Duncan Windsor—Tecumseh 1995–2013 Cabinet minister 2003–13Deputy Premier 2011–13 exCity Windsor City Councillor 1988–94 ExMPP Cen Barrie 2014-2018 ExMPP Tor. Etobicoke West 1987-1990 ExMPP Tor. Davenport 2014-2018 Cabinet minister 2006–07 ExMPP North Thunder Bay—Atikokan 1987–2003 OLP leader 1992–1996Cabinet minister 1987-1990 ExMPP East Ottawa—Vanier 2003–2016 Cabinet minister 2003–16 ExMPP Tor. Etobicoke—Lakeshore 2014–18 Cabinet minister 2017–18 ExMPP Cen Richmond Hill 2007–18 Cabinet minister 2013–18 ExMPP Tor. St. George—St. David 1993–95 Chief of Staff to the Prime Minister 2003–06 ExMPP Cen Mississauga North 1985–95 Cabinet minister 1989–90 ExMPP SW Elgin—Middlesex—London 1999–2011 Cabinet minister 2003–07Speaker 2007–11 ExMPP Tor. Scarborough—Agincourt 1987–2011 Cabinet minister 1987–90, 2003-11 ExMPP East Glengarry—Prescott—Russell 2018–22 ExMPP Cen Wentworth North 1985–90 Cabinet minister 1987–90 ExMPP Tor. Scarborough—Agincourt 2011–18 ExMPP SW Windsor—Sandwich 1981–90 Cabinet minister 1985–90 MPs MP East Nepean 2015–present MP Cen Niagara Centre 2015–present MP Tor. Yvan Baker Etobicoke Centre 2019–present exMPP Etobicoke Centre 2014-18 MP Cen St. Catharines 2015–present MP Cen Hamilton East—Stoney Creek 2021–present MP East Glengarry—Prescott—Russell 2015–present MP Tor. Willowdale 2015–present MP Cen Mississauga—Erin Mills 2015–present MP Tor. Etobicoke-Lakeshore 2015–present MP Tor. Eglinton-Lawrence 2015–present federal minister 2019–23 MP Cen Aurora—Oak Ridges—Richmond Hill 2021–present MP North Nickel Belt 2015–present MP Tor. Humber River—Black Creek 1997–present federal minister 2003–05 exCity North York/Toronto Councillor 1987–99 MP Cen Vaughan—Woodbridge 2015–present MP Cen Mississauga—Streetsville 2021–present Former federal parliamentarians ExMP Cen Bramalea—Gore—Malton 1997-2011 ExMP Cen Markham 2000-17 Cabinet minister 2002-06, 2015-17, Canadian Ambassador to China 2017-19 ExMP Tor. Beaches—East York 1993-2011 federal minister 1999–2002 ExMP Cen Newmarket—Aurora 2015–2019 ExMP East Northumberland—Peterborough South 2015–2019 Municipal elected officials City East Ottawa-Carleton District School Board Trustee since 2010 City Cen Milton Town councillor & regional councillor for Ward 3 2022–present City North Greater Sudbury Councillor 2022–present City Cen Chair of the District of Muskoka 2022–present Mayor of Barrie 2010-22 City Cen School Trustee in Mississauga 2022–present City North Mayor of Hearst since 2002 City Cen Mississauga City Councillor 2022–present 2020 OLP leadership contestant City East Ottawa City Councillor Former municipal elected officials exCity North Mayor of Greater Sudbury 2010-2014 Other notable endorsements Misc Tor. The Toronto Star References for endorsements of Bonnie Crombie

Nathaniel Erskine-Smith Endorser Constituency represented Other roles held, notes MPPs MPP East Kanata—Carleton 2023–present ExMP Kanata—Carleton 2015-21 MPP Tor. Beaches—East York since 2022 ExCity Toronto City Councillor for Ward 32Beaches-East York 2010-18 Former MPPs ExMPP Tor. Eglinton 1987-1995 ExMPP Tor. Beaches—East York 2014-2018 MPs MP Cen Oakville North—Burlington 2015–present MP Tor Toronto—Danforth 2015–present MP SW London North Centre 2015–present MP North Sudbury 2021–present MP North Thunder Bay—Rainy River 2019–present MP (n/a) Fredericton (New Brunswick) 2019–present MP (n/a) Bourassa (QC) 2014–present MP (n/a) Laval—Les Îles (QC) 2015–present MP (n/a) Mount Royal (QC) 2015–present MP (n/a) Saint-Laurent (QC) 2017–present MP (n/a) Saint John—Rothesay (NB) 2015–present MP (n/a) Malpeque (PEI) 2021–present MP (n/a) Brossard—Saint-Lambert (QC) 2015–present bgcolor=#CCC MP (n/a) Longueuil—Charles-LeMoyne (QC) 2015–present MP (n/a) Vaudreuil—Soulanges (QC) 2015–present MP (n/a) West Vancouver—Sunshine Coast—Sea to Sky Country (BC) 2019–present Former federal parliamentarians ExMP East Neil Ellis Bay of Quinte 2015–21 City Mayor of Belleville 2006–14 & 2022–present ExMP East Ottawa Centre 2015-2021 Cabinet minister 2015-21 ExMP Tor. (Ontario Senator 1984–92 ExMP North Kenora—Rainy River 1988-2004, Kenora 2015–19 Cabinet minister 1999-2003 ExMP SW London West 2015–2021 ExMP (n/a) Pierrefonds-Dollard (QC) 2015–19 Municipal elected officials City North Thunder Bay City councillor 2014–present City SW Sarnia city councillor 2003-18 & 2022–present Former municipal elected officials Other prominent individuals Other North elected Chief of Ojibways of Onigaming First Nation References for endorsements of Nate Erskine-Smith Ted Hsu Endorser Constituency represented Other roles held, notes Former MPPs ExMPP East Kingston and the Islands 1995–2014 Cabinet minister 2003–2014 exCity Mayor of Kingston 1980–88 ExMPP SW Huron—Bruce 2003–2011 Cabinet minister 2010–2011 ExMPP Cen York Centre 1985–1995, Vaughan 2001–2012 Cabinet minister 1985–1990, 2003–2005, 2006–2007 MPs MPP East Kingston and the Islands 2015–present exCity Mayor of Kingston 2010–14 Former federal parliamentarians ExMP East Hastings—Lennox and Addington 2015-2019 ExMP East Kingston and the Islands 1988-2011 Speaker of the House 2001-2011 ExMP SW Guelph 2008-2015 ExMP North Thunder Bay-Superior North 2008-15 (NDP/Green MP), Deputy Leader of the Green Party of Canada Municipal elected officials City East Councillor District 6, Kingston City Council ExCity East former Storrington Township Councillor Other prominent individuals Other Lead Guitarist for The Tragically Hip References for endorsements of Ted Hsu Yasir Naqvi