So what do they do now?

All was going quite splendidly. Over a period of almost two years, Justin Trudeau's Liberals maintained a tidy lead on the governing Conservatives. Nothing Prime Minister Stephen Harper tried seemed to boost his declining fortunes.

To alter the prevailing mindset, which favoured change, something freakish had to happen.

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What happened was the news story of the year. The deranged gunman's attack on Parliament was a mood-altering event. It elevated national security to a prime place on the issues ladder. Mr. Harper's numbers rose, Mr. Trudeau's receded. The lead has almost disappeared.

Liberals aren't panicking. "The strategy has been to force the other two parties to put out the main platforms first, which they have now done," a top strategist wrote in an e-mail. "We have a big clear target to shoot at with our own."

Are they moving up their policy release dates? "Given that we aren't using the public's money to advertise our platform, as Harper is, that would be ill-advised."

What is encouraging for them is the decline of the New Democrats outside Quebec. A two-horse race between progressives and the Harper right is "the best set of circumstances we could hope for."

Three scenarios are being taken into account, the strategist noted. A spring election, a fall election, a Harper resignation. "Anything less than a majority government is a loss for Harper, which he knows."

The momentum shift, fortune's turn toward the Tories, is not disputed. That turn included the Jian Ghomeshi scandal, which suits the CBC-loathing Prime Minister just fine – all the more so because it spun off into sexual-harassment allegations involving the opposition parties, which has tied them in knots.

Behind the headlines, the Liberals are trying to put together a policy playbook that can sell. On the economy, a caucus member said, look for a focus on "infrastructure, infrastructure, infrastructure." On criminal justice, reported another, reforms will be aimed at repealing the 19th-century fill-the-jails model the Conservatives have put in place. There will be an activist approach on health care to address Canada's plunge in the rankings among countries with universal care systems. According to one study, Canada went from fourth of 11 countries a decade ago to 10th today.

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On the military, the Liberals will be exploiting the government's shabby treatment of veterans. On the environment and climate change, they have big openings. On ethics, we can expect a big reform package to underline the Conservatives' sorry record, illustrated by the Senate expenses scandal.

To contrast a Prime Minister who has refused to sit down with the premiers in first ministers' conferences, the Liberals will likely highlight co-operative federalism: Just because meeting with all the premiers can be risky business doesn't mean that you run and hide. Other prime ministers, as they correctly point out, did not display that kind of cowardice.

Playing the waiting game on policy pronouncements may work in Mr. Trudeau's favour because his party will be in a position to respond to the initiatives of the others and occupy flanks not taken. It will also leave Mr. Harper's heavily financed advertising machine with fewer Liberal targets.

The more important consideration, as former PM Jean Chrétien noted in a recent chat, is the mood of the people. The party in sync with the national mood wins, he said.

The key questions now are how much the mood has changed as a result of the trauma of Oct. 22 and how long this change will last. The story of the year favoured the Conservatives because it increased the appetite for a leader who brings stability, not change.

Most, including Mr. Chrétien, seem to believe that its impact won't last much beyond the start of the new year. But there are a lot of ways for the Conservatives to keep the fear card alive. Unforeseen occurrences, such as another terror strike, could work in their favour as well.