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An NDP shirt adorned with campaign pins is shown at the NDP convention in Hamilton, Ont., in October, 2023. The party’s new leader will be chosen at next year’s leadership convention in March.Peter Power/The Canadian Press

Left-wing activist Yves Engler on Monday formally applied to join the NDP leadership race, saying he has already raised $90,000 of the $100,000 required to stand, even though his candidacy has not yet been approved by the party.

Mr. Engler, a prominent pro-Palestinian activist with a history of confronting politicians in public places and posting their reactions to his questions on social media, will now face vetting by the NDP, a requirement for all candidates.

NDP leadership race chief electoral officer Éric Hébert-Daly has previously raised concerns about Mr. Engler soliciting donations for his campaign before being approved as a candidate.

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From left, NDP leadership candidates Tanille Johnston, Avi Lewis, Tony McQuail, Heather McPherson and Rob Ashton stand with Canadian Labour Congress president Bea Bruske ahead of the NDP Leadership forum in Ottawa on Oct. 22.Spencer Colby/The Canadian Press

Several candidates have so far been approved by the NDP to take part in a race to succeed former leader Jagmeet Singh. They include MP and foreign affairs critic Heather McPherson; Avi Lewis, a documentary filmmaker who teaches at the University of British Columbia; Rob Ashton, a B.C. union leader; Tanille Johnston, a social worker; and Tony McQuail, an organic farmer.

They are listed as official candidates by Elections Canada and are bound by its rules for leadership campaigns.

Mr. Engler is backed by the socialist caucus of the NDP. He expressed concern on Monday that the vetting committee will ban him from standing. Earlier this month, he said the NDP vetting process would have been unlikely to approve mayor-elect of New York City Zohran Mamdani. The process requires candidates to list statements they’ve made “which have/may be considered politically ‘controversial,’” he added.

“Party vetting is a threat to democracy,” Mr. Engler said in an e-mail Monday. “Differences of political opinion should be determined by the membership, not a three-person back-room committee.”

“NDP members should be allowed to decide whether they support or oppose a candidate calling for the party to vote down a budget that plows tens of billions of dollars more into a military that is structured to assist the U.S. machine,” he wrote.

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Former NDP MP Kennedy Stewart said the party’s vetting process is rigorous and looks at social-media posts, statements that have been made and publications. He said the party would seek to protect its brand and will not want any surprises that could damage their electoral prospects.

The vetting process will likely look at past criminal convictions and time spent in jail. Mr. Engler spent several days behind bars earlier this year after being accused of harassment of a journalist and social media influencer, but the charges were subsequently dropped.

Mr. Engler is due to appear in court later this month on charges of harassment against a Montreal police officer. He had urged his supporters to e-mail the police to ask them to drop the charges of harassment against the social media influencer, who has now brought a defamation case against him.

The NDP did not immediately respond to a request for comment.