Lionel Perez is taking over as interim leader of Équipe Denis Coderre, after the man the party is named after stepped down following his election loss Sunday.

Perez, a city councillor for the Darlington district in Côte-des-Neiges–Notre-Dame-de-Grâce, will guide the party through a transition period — and help come up with a new name. 

While Denis Coderre is quitting municipal politics, his party still holds 25 of 65 seats on city council. Projet Montréal won a slim majority, for a total of 34.

Speaking to reporters Thursday, Perez promised a strong opposition, one that would recognize the good deeds of Projet Montréal​ but take them to task when required.

Perez also denied the Coderre administration is leaving behind a $358-million budget shortfall, as Projet Montréal​ has suggested. He called the move by the incoming administration "the oldest trick in the book."  

Perez offered his take on Projet Montréal's "astonishing win" in a lengthy Facebook post earlier this week. He was surprisingly blunt about his party's own failings, saying the campaign suffered from "serious deficiencies." 

Projet Montréal, on the other hand, "picked a few key issues (no doubt after detailed polling) and hammered their message and convinced people (even though I factually disagree with many of their assertions)," he wrote.

"Since they could not beat us on our record, they made it into a referendum on Denis Coderre's personality instead. The omni-mayor's greatest asset became his greatest liability."

With files from Sean Henry