Ontario Liberal nomination fallout just deepened this Tuesday as Liberal MP Nate Erskine-Smith formally challenged the results of the party’s contentious Scarborough Southwest nomination race, alleging voting irregularities and calling for the outcome to be overturned.

In a notice of appeal filed with the Ontario Liberal Party’s arbitration board, Erskine-Smith argued the May 9 nomination was marred by what he described as “serious irregularities,” including concerns about voter identification procedures and discrepancies in the ballot count.

The appeal comes after Erskine-Smith lost the nomination to businessman Ahsanul Hafiz by just 19 votes: a razor-thin margin that immediately sparked accusations from the longtime Toronto MP and his campaign team.

According to the filing, the campaign alleges there were more ballots counted than registered voters who cast them. The appeal also raises questions about how identification rules were enforced during the vote, an issue Erskine-Smith publicly referenced in the hours after the results were announced Saturday night.

The Ontario Liberal Party confirmed this Tuesday that it had received part of the appeal documentation and was expecting the remainder later in the day. Party officials have so far defended the process and rejected suggestions the race was improperly conducted.

Interim Liberal leader John Fraser struck a dismissive tone when asked about the controversy at Queen’s Park earlier this Monday, insisting the nomination had been administered fairly.

“We ran a fair and free nomination,” Fraser told reporters Monday, noting dozens of party volunteers and officials oversaw the process. “If people have concerns, they should prove it.”

The dispute has exposed growing tensions inside the Ontario Liberal Party at a sensitive moment, just months before members are set to choose a permanent leader in November.

Erskine-Smith had been widely viewed as a potential frontrunner in that leadership race and was attempting to transition from federal to provincial politics through the Scarborough Southwest byelection. He previously said he intended to resign his federal seat once Premier Doug Ford called the provincial contest, which is expected later this year.

The Beaches–East York MP has represented the riding federally since 2015 and has built a profile within Liberal circles as an outspoken and often independent-minded figure. But throughout the nomination contest, he repeatedly voiced concerns about the Ontario Liberals’ membership verification system and suggested elements of the party establishment were working against his candidacy.

Meanwhile, Hafiz has moved quickly to project unity after the win. On Monday, the Ontario Liberal caucus invited him to Queen’s Park to meet with MPPs as the party begins preparing for the upcoming byelection.

Speaking to reporters, Hafiz said he had not yet spoken directly with Erskine-Smith following the result and was focused on the general campaign ahead.

The Scarborough Southwest seat became vacant earlier this year after former NDP deputy leader Doly Begum resigned to run federally for Prime Minister Mark Carney’s Liberals.

The riding has elected New Democrats provincially in each of the last three elections, but Liberals see the upcoming byelection as an opportunity to rebuild support in Toronto ahead of the next general election.

The Ontario Liberal Party is scheduled to elect its next permanent leader on Nov. 21.