Yes it's only one poll, and yes it's only halfway through the mandate, but Liberals should be worried by last week's Ipsos survey, for two reasons:

First, the Conservative coalition that sustained Stephen Harper's governments appears to be realigning.

Second, the agenda may be shifting away from social issues and toward economic management, which is good for Conservatives and bad for Liberals.

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This does not mean the Tories are favoured to win the next general election. But it does mean that a prior assumption – that the Liberals were unbeatable – no longer holds. This is a whole new political ball game.

Up until last week, all Ipsos polls showed the Liberals and the Conservatives more or less where they were on election night. The Omar Khadr affair, Andrew Scheer becoming Conservative leader, Jagmeet Singh becoming leader of the NDP – nothing seemed to move the needle.

And so it came as something of a shock when Ipsos reported that Liberal support had suddenly swooned to 33 per cent, while the Conservatives had surged to 38 per cent, with the NDP earning the support of one voter in five.

The pollster was in the field as the fallout from Mr. Trudeau's India trip splashed across people's screens, suggesting strong public disapproval of the Prime Minister's performance.

But was this simply a bad week that the Liberals will get over, or a tipping point? It's far too soon to say. But what is interesting about the poll is where the Liberals are doing badly.

In the Prairie provinces, support for the Grits has tanked. If an election were held tomorrow, the party would lose half a dozen seats or more in that region.

Melanee Thomas, a political scientist at University of Calgary, believes that the 2015 election represented "the absolute high water mark" of support for Liberals in the Prairie provinces, where anti-Liberal sentiment is broad and deep. "The only place the party can go is down."

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Alberta voters, especially, blame the federal Liberals for the lack of progress in getting pipelines built, she said.

The Conservatives are also seven points ahead of the Liberals in Ontario. This could be crucial.

Stephen Harper's conservative coalition consisted of voters in the Western provinces and in the 905 – the band of suburban cities surrounding Toronto. The Ipsos poll suggests that coalition may be re-emerging.

"If I were the Liberals I would be worried about their support in Ontario," says Henry Jacek, a political scientist at McMaster University in Hamilton. "I do think that the shift in public opinion is substantial and started even before the India trip."

Support for this government rests very much on the personality of the Prime Minister, he believes. If Mr. Trudeau's public image is shifting from charismatic to cartoonish, the Liberals could be in serious trouble.

Or not. A Nanos poll released Tuesday shows the Liberals maintaining a narrow lead over the Conservatives.

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But as my colleague Bill Curry reports, internal government surveys show that voters are worried about the chronic deficits run up by the Trudeau government.

And with the NAFTA talks dragging on inconclusively, compounded by President Donald Trump's threat to slap tariffs on Canadian steel and aluminum exports, protecting the Canadian economy could become the most important issue facing the country.

Peter Graefe, also of McMaster, observes that "in terms of long-term issue ownership," economic issues "probably play to the strengths of the Conservatives."

Beyond that, Prof. Graefe suspects that less affluent and well-educated Ontario voters may be losing patience with a Liberal government that focuses on progressive social issues, "but which is in some ways disconnected from actually dealing concretely with the lived realities of important segments of the Ontario population, where the economic growth has been positive but small for a decade, and people don't really feel a sense that much is changing."

To their credit, Mr. Trudeau's team has made protecting free trade with the United States a top priority. But Finance Minister Bill Morneau's 2018 budget focused more on gender, environmental and Indigenous issues than on economic fundamentals.

Are the Liberals chasing the wrong priorities as the Canadian economy confronts American-generated headwinds?

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We'll see. But politicians and political watchers should pay heed to the Ipsos poll, while we wait to learn whether this shift is temporary, or something big.