Toronto ? Canada’s opposition parties have agreed in principle to form a coalition that would topple Prime Minister Stephen Harper’s Conservative government, an official said, though infighting among one of the parties cast doubt on whether such a bloc would hold.

The opposition Liberals, New Democrats and Bloc Quebecois, the parties that would make up the new bloc, say that Harper has no solid plan to deal with the global economic crisis.

Harper’s party won enough votes in the Oct. 14 national election to stay in power, but its hold is tenuous because it did not win a majority of Parliament’s 308 seats. The party must rely on opposition support to pass budgets and legislation.