<P> In practice, however, the House of Commons is the dominant chamber of Parliament, with the Senate very rarely exercising its powers in a way that opposes the will of the democratically elected chamber . The last major bill defeated in the Senate came in 2010, when a bill passed by the Commons concerning climate change was rejected in the Upper House by a vote . </P> <P> A clause in the Constitution Act, 1867 permits the Governor General (with the approval of the Queen) to appoint up to eight extra senators to resolve a deadlock between the two houses . The clause was invoked only once, in 1990, when Prime Minister Brian Mulroney advised the appointment of an additional eight senators in order to secure the Upper House's approval for the Goods and Services Tax . </P> <P> Though it does not formally elect the prime minister, the House of Commons indirectly controls the premiership . By convention, the prime minister is answerable to, and must maintain the support of, the House of Commons . Thus, whenever the office of prime minister falls vacant, the governor general has the duty of appointing the person most likely to command the support of the House--normally the leader of the largest party in the lower house, although the system allows a coalition of two or more parties . This has not happened in the Canadian federal parliament, but has occurred in Canadian provinces . The leader of the second - largest party (or in the case of a coalition, the largest party out of government) usually becomes the Leader of the Official Opposition . Moreover, the prime minister is, by unwritten convention, a member of the House of Commons, rather than of the Senate . Only two prime ministers governed from the Senate: Sir John Abbott (1891--1892) and Sir Mackenzie Bowell (1894--1896). Both men got the job following the death of a Prime Minister, and did not contest elections . </P> <P> The prime minister may only stay in office as long as he or she retains the confidence of the House of Commons . The lower house may indicate its lack of support for the government by rejecting a motion of confidence, or by passing a motion of no confidence . Important bills that form a part of the government's agenda are generally considered matters of confidence, as is any taxation or spending bill and the annual budget . When a government has lost the confidence of the House of Commons, the prime minister is obliged to either resign, or request the governor general to dissolve parliament, thereby precipitating a general election . The governor general may theoretically refuse to dissolve parliament, thereby forcing the prime minister to resign . The last instance of a governor general refusing to grant a dissolution was in 1926 . </P>

Does canada's prime minister hold a seat in the house of commons