Guy Giorno, Prime Minister Stephen Harper’s most senior adviser, is stepping down, as the Conservatives seek to recalibrate after a politically troubled summer.

Mr. Giorno, who has been Mr. Harper’s chief of staff since July, 2008, will leave his post by the end of the year, sources say. He recently became a father again and reportedly wishes to spend more time with his wife, son and newborn daughter.

Mr. Giorno is credited with bringing increased organizational discipline to the Prime Minister’s Office. But he has also been the focus of much criticism, some of it reportedly from within the government’s own ranks, as the Conservatives squandered last autumn’s 10-point lead in the polls through one political misstep after another.

Recent surveys by Harris-Decima, Ipsos Reid and EKOS have the Conservatives and Liberals essentially tied. The controversy over proroguing Parliament, the fight over the Afghan detainee documents, the billion-dollar summits, the flap over killing the mandatory census, the efforts to kill the gun registry, the fury of the veterans ombudsman and other controversies have conspired to erode support for the Conservatives.

Mr. Harper has decided that the next chief of staff will come from outside the ranks of the Prime Minister’s Office, which was the case for Mr. Giorno, a lawyer who had served as principal adviser when Mike Harris was Ontario premier.

In part because of that lineage, Mr. Giorno was seen by some as a hyper-partisan neoconservative whose obsessive need to score political hits on the opposition actually did the Conservative cause more harm than good.

The news for the Liberals is not entirely benign. Michael Ignatieff spent the summer on the road while Mr. Harper largely confined himself to the government’s Harrington Lake retreat until mid-August. Yet despite the media exposure and the Conservatives’ travails, the Liberal Leader wasn’t able to move the polls more than a few percentage points.

The Conservatives believe their successful handling of the recession will serve as the anchor of its eventual election message. Mr. Harper has also managed to finally assemble a coherent foreign policy: stand by the United States, but woo the Chinese and Indians, while asserting sovereignty in the North and focusing aid on Africa, Afghanistan and Haiti.

And the Conservative Leader is already test-driving what will doubtless become a relentless message: that Canada is really a two-party state, with the Conservatives on one side and a “coalition,” as he calls it, of the Liberals, the NDP and the Bloc Québécois on the other.

Never mind that the other parties don’t think of themselves as a coalition. It is Mr. Harper’s political good fortune that a coalition is governing Britain and will eventually be cobbled together in Australia. And a coalition is just what Mr. Ignatieff’s predecessor, Stéphane Dion, attempted. So the idea is in the air.

Mr. Ignatieff has already constructed his counter-narrative: The Conservatives are irrational and cruel. Irrational, because they spend billions on new prisons even though crime is going down, and they dismembered the mandatory long form of the census even though this will deprive governments at all levels of essential knowledge.

Cruel, because the Tories will have to cut program spending as the federal government moves toward a balanced budget.

These competing narratives will dominate the next election whenever it comes. It will almost certainly not be this fall, because no party stands to gain much at this stage, but may well be in the spring, because it will be very hard for the Liberals to support the next budget.

The Conservatives still have reason to feel better about that election than the Liberals for one simple reason: Year after year, since around 2006, only about one voter in four can be counted on to vote Liberal, except for brief periods when a few more join them. But one in three votes Conservative, except for brief periods when the Tories’ mistakes drive the numbers down.

This will be solace for Mr. Harper, whatever the poll numbers, as he prepares for autumn and a new chief of staff.