Leader of the Opposition in the Canadian Senate

In Canada, the Leader of the Official Opposition in the Senate (French: Chef de l'opposition au Sénat) is the leader of the largest party in the Senate not in government.

Even though the position's name is very similar to the Leader of the Opposition in the House of Commons (the Opposition House Leader), the Leader of the Opposition in the Senate's role is more analogous to the Leader of the Official Opposition because its holder is the leader of the party's Senate caucus. The responsibilities that, in the House of Commons, are done by the house leaders—including day-to-day scheduling of business—are undertaken in the Senate by Government and Opposition deputy leaders and Opposition whips.

Since it is the Canadian House of Commons that determines what party(ies) form government, the size of party caucuses in the Senate bear no relation to which party forms the government side in the Senate and which party forms the opposition. Thus, the Leader of the Opposition in the Senate may lead more Senators than the Leader of the Government in the Senate. Since, normally senators have longer tenure than MPs, this is often the case immediately following a change in government, until the new prime minister can appoint more people from their party.

The Leader of the Opposition in the Senate is not necessarily from the same party as the opposition in the House of Commons. From 1993 until 2003 the Leader of the Opposition in the Senate was a Progressive Conservative despite the fact the Progressive Conservatives were not the Official Opposition in the House of Commons. The Official Opposition in the Commons; (Bloc Québécois, Reform, Canadian Alliance) did not have Senate representation. This scenario repeated itself following the results of the 2011 election that saw the Liberal Party lose Official Opposition status in the House to the New Democratic Party — since the NDP has no representation in the Senate (and favours abolition of the chamber) the Liberals would form the Official Opposition in the Senate.