From an interview with Peter Mansbridge

"If it's a problem for a significant number of Canadians and if it's a liability that may keep Mister Harper in power it prevent us to do the three-pillar approach that I want to be true for Canada, to bring together more than any other country in the world economic prosperity, social justice, environmental sustainability, then I will do this sad thing, then, to renounce to my French citizenship that I receive from my mother."