The streets of Toronto’s Forest Hill neighborhood are lined with arching maple trees and multimillion-dollar homes, a plummy refuge for some of Canada’s wealthiest families and top business leaders. Now it’s also a red-hot political battleground in the fight to control the country’s highest office.

On Monday, residents of this part of Toronto will vote in a closely watched special election for a vacant seat in the House of Commons. For Prime Minister Justin Trudeau, who has held power since 2015 by consistently winning big in Canada’s largest city, the stakes are high. A loss would dramatically raise the pressure on the embattled leader to quit ahead of a national election expected next year.