Only 99 votes separated Leclerc, who took 36.7 per cent of the vote, from the Union Montreal candidate, Nino Colavecchio, with 34.8 per cent. Projet Montréal's Nathalie Pierre-Antoine came third, with 28.6 per cent of the vote.
Turnout was poor, with just 21 per cent of eligible voters casting a ballot.
"It shows, of course, that citizens here voted for change," declared Leclerc, calling her victory a vote for integrity and a sign there's "a wind of change."
Process to elect new mayor begins
The process to elect a mayor to replace Tremblay gets underway Monday afternoon, when the city council holds a special meeting to table a notice of the mayor's vacant position.
Council members from any party who wish to put their names forward can submit their intention beginning Tuesday. The deadline is 4:30 p.m. Thursday.
If only one person steps forward, he or she will be acclaimed as mayor on Thursday. Otherwise another council meeting is set for Friday morning, when the mayor will be elected by secret ballot.
Union Montreal in turmoil
The shake-up at city hall since Tremblay's departure is causing turmoil within the ranks of the former mayor's party.
The first sign of quarreling came Friday, when Côte-des-Neiges—Notre-dame-de-Grâce borough mayor Michael Applebaum quit as the chair of Montreal's executive committee.
A Union Montreal borough councillor for Rivière-des-Prairies-Pointe-aux-Trembles, Giovanni Rapanà, announced Monday he will sit as an independent.
He refused to give the reasons for his departure from Union Montreal.
Coming on the heels of Leclerc's byelection win Sunday, Rapanà's defection is another sign Union Montréal's declining support in the borough.
His departure leaves Union Montreal with no representation in the east-end borough.