Normally, a very select committee would be holding its first meeting, round about now, as the search begins for a new governor-general. If that committee exists, it should be disbanded.

Stephen Harper should ask Governor-General David Johnston to stay at his post for a sixth year, and he should announce that extension now. Otherwise, a complete novice could arrive at Rideau Hall unprepared for interesting times.

By convention, the head of state in Canada serves for a five-year term, although that convention isn't ironclad. For example, Vincent Massey (1952-1959), Canada's first Canadian governor-general, George Vanier (1959-1967), its most beloved, and Roland Michener (1967-1974), his successor, all served approximately seven years.

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More recently, Adrienne Clarkson (1999-2005) served six years, and that is the precedent we need to consider here.

In the wake the June 2004 election, Paul Martin had formed a weak minority Liberal government that the opposition Conservatives, NDP and Bloc Quebecois were threatening to bring down as soon as Parliament convened in early October.

Whether Mr. Martin would ask for a dissolution and a new election in the event his government was defeated, whether the governor-general would grant that request, or whether then-opposition leader Stephen Harper would be asked to form a government was a matter of considerable debate.

Mr. Martin asked Ms. Clarkson to stay on for a sixth year. Canada would have needed her experience and judgment in the event of a parliamentary crisis. We face the same possibility today.

Canada's 28th governor-general has served his country well. Mr. Harper asked Mr. Johnston to expand the governor-general's contribution to economic diplomacy. He has travelled the globe representing Canada in 31 countries, seeking to increase goodwill between this country and China, South Korea, India and other trading partners, even as officials sought to negotiate closer economic ties.

Such travel can be exhausting, and it would be understandable if Mr. Johnson, who is 73, wanted to hang up his gloves. Unfortunately, we can't let him.

Mr. Johnston's tenure will end October 1, smack in the middle of the general election. A new G-G would have to be sworn in either before the writ is dropped in early September, or after the Oct. 19 poll. In either case the timing would be awful.

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We could have a hung Parliament. We could have the Liberals and the NDP proposing to enter into a coalition. We could have Mr. Harper trying to form and maintain a minority Conservative government.

This would be no time for a new and untested governor-general to confront a constitutional maze. Mr. Johnston has already been on the job four and a half years. He is a recognized authority in constitutional law. He has acquitted himself admirably from his first day in office. He needs to stay.

There is one alternative. Mr. Harper could announce a new governor-general within the next few weeks, who could be sworn in in June. This would give the new G-G the summer to swot constitutional law. But the optics would be terrible. Mr. Harper would be implicitly admitting that he feared defeat on Oct. 19 and was determined to impose his choice on his successor.

No, the prime minister of the next government – whether it is Mr. Harper, Thomas Mulcair or Justin Trudeau – should have the time and liberty to appoint a selection committee and then to choose Mr. Johnston's successor from whatever shortlist the committee provides.

Mr. Harper might also consider asking Mr. Johnston to serve until the end of 2017. The prime minister would be hard pressed to find an abler governor-general to represent and speak for the best that is Canada during its sesquicentennial.

But whatever Mr. Harper decides, he should decide it now, not least so Mr. Johnston has time to prepare.

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Those who know this governor general well speak of his deep sense of duty to community and country. He will surely stay on, if asked. Mr. Harper should ask.