The borough mayor's four councillors confirmed they will also be leaving the party.
"We respect the people that are in [Union Montréal] just the same, they are good people. I think they have decisions to take in the future. I'll leave it up to them," said Miranda.
Miranda is the third person to announce his departure from the party in less than 24 hours, following Chantal Rossi and Gilles Deguire's resignations yesterday.
Party member Alan DeSousa said the departures come as no surprise in light of the municipal election scheduled for November 2013.
"You'll find that the months of January, February were always rock'n'roll and usually, by the time you get to June, things straighten out and the race begins," he said.
Radio-Canada is also reporting that Saint-Léonard borough Mayor Michel Bissonnet is considering a departure from the municipal party.
Rossi, a borough councillor for Montreal North and Deguire, the mayor of Montreal North, left the party less than 48 hours after Quebec's anti-corruption squad raided Union Montréal's offices on Tuesday.
The squad also searched city hall and six borough offices.
It's believed the raids are related to a $100,000 invoice, which may be tied to allegations of illegal fundraising practices within the Union Montréal party, according to sources cited by Radio-Canada.
"They're trying to find a needle in a haystack," said Jacques Duchesneau, the Coalition Avenir Québec critic for public security
Duchesneau said he remains supportive of Mayor Michael Applebaum.
Wave of departures from Union Montréal
The two are the latest in a wave of departures from the former majority party following former mayor Gérald Tremblay's resignation. Tremblay was the head of Union Montréal before his resignation in November.
Deguire, who will continue to sit on city council as an independent, said he has not been satisfied with the evolution of his party since Tremblay left.
"The flame is no longer there," he said.
Deguire said he believes Montreal needs a new leader and told reporters yesterday that Mayor Michael Applebaum "is not my friend."