Nik Nanos is The Globe and Mail's pollster and the executive chairman of Nanos Research.

In the stock market, it's called the technical correction. That's when the price of a stock decreases after a run of price increases. One can easily argue that the federal Liberals are headed toward a political technical correction. Since their victory in 2015, it sure has been political sunny days with a very long political honeymoon.

The latest Nanos weekly tracking has the Liberals at 43-per-cent support, followed by the Conservatives at 28 per cent, the New Democrats at 16 per cent, and the Bloc Québécois and the Greens at 6 per cent. Liberal support now is higher than when they won their majority in 2015.

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The reality is that their double-digit advantage over the Conservatives should give them cold comfort. The strength of the federal Liberals in the polls is a combination of factors, including delivering on the promise to govern differently than the previous Harper government, but one should not underestimate the absence of an alternative for voters to mobilize around.

This is akin to owning the only restaurant in town and thinking you are a brilliant cook. Perhaps your success is more about being the only place in town to eat. The same holds true for the Liberals – with both the Conservatives and the New Democrats lacking permanent leaders, the Liberals are currently the only thing on the political menu.

The Liberals should brace themselves for their own political technical correction that will recalibrate their level of support. There are two key factors to watch for: the election of permanent leaders for the Conservative Party and the NDP, and the trajectory of the Liberal trend line.

On the vacancy filling front, the upcoming Conservative leadership decision will be one of two moments where the true level of support for the Liberals will regulate itself. Will there be a post-leadership honeymoon for the new Conservative leader? It is too early to tell. With Liberal support so high, one should watch to see if the new Conservative leader can appeal to soft Liberals who in the past voted Conservative, but opted for change in 2015.

The NDP leadership race this fall will be the second moment where Liberal support could be adjusted. The election of a new NDP leader could potentially be more telling in terms of Liberal support because of the proportion of Canadians who are Liberal-NDP switchers. One can argue that with the past election being about change, it was those Liberal-NDP switchers who made Justin Trudeau Prime Minister. On the first day of the federal election in 2015, when Canadians were asked who they preferred as PM, Stephen Harper topped the list, followed by Tom Mulcair and then Justin Trudeau as the third choice. Fast forward through a long campaign and Mr. Trudeau hopped over Mr. Mulcair as the key challenger to Mr. Harper and eventually overtook Mr. Harper to win the election and become Prime Minister.

For those armchair political strategists, you will have to wait until both the Conservatives and the New Democrats elect their leaders to find out how the technical correction in Liberal support plays out.

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The second key factor that the Liberals should brace for is the trajectory of the change in public opinion. Because the Liberals are currently riding exceptionally high levels of support, the trajectory of their support in the future is most likely to be negative (except, of course, if the opposition parties falter). Assuming some sort of negative trajectory, the key question is how steep that negative trajectory might be. Experience in the past suggests that it is not enough for the opposition parties to do things right – they need the help of the Liberals to drive the trend line. Help would be the Liberals making unforced errors, looking disconnected from the priorities of Canadians or the Prime Minister himself making a mistake.

If the Conservatives and the New Democrats do a good job of transitioning to new leaders, you can expect an incremental shift in opinion. If at the same time the Liberals make mistakes, then you can expect the velocity of change in opinion to quicken.