Polls showing the leaderless Liberals within a stride of the Harper Conservatives for the first time since 2010 has some Grits imagining their party has risen from its electoral death bed, and is miraculously back in the running for the keys to 24 Sussex Drive.

With Justin Trudeau a good bet to win the Liberal leadership next month, the latest polling numbers would seem to indicate the party's rising fortunes are being driven by an outbreak of Trudeaumania Jr. among Canadian voters.

If only politics and polling were that simple.

The national polling firm Nanos Research has been tracking party standings every month for the past 10 years, and from that some clear patterns emerge.

First, the Liberal party has generally been most popular when it has not had a leader, or at least when it is facing the prospect of being leaderless.

When Michael Ignatieff quit as Liberal leader following the 2011 election, the party's standings jumped until Bob Rae took over as interim leader.

Since Rae announced he would not seek the leadership, leaving the party truly leaderless until next month's convention, Nanos shows the Liberals rebounding to the current statistical tie with the Conservatives.

The same happened when Stephane Dion stepped down in 2008, and even when Paul Martin quit after the Liberals' 2006 electoral defeat. In both cases, Liberal fortunes jumped.

Notably, the Liberals reached their greatest popularity in two decades in 2003 — as Jean Chretien was packing his bags to leave office.

Short honeymoon

Other than being worth more to their party when gone than when in office, Liberal leaders over the past decade have shared something else in common: a short honeymoon.

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Liberal leadership hopefuls Justin Trudeau and Martin Cauchon have a mock battle following a recent candidates' debate. The real fighting is still to come. (Andy Clark / Reuters)

The Nanos tracking shows Ignatieff, Dion and Martin all at their peak the day they won their respective leadership races, followed within months by a steep decline in popularity.

All of which may help to explain the leaderless Liberals' current rise in the polls, and would appear to provide a cautionary tale for Trudeau, or whomever the party chooses to take over the helm.

Nik Nanos, president of Nanos Research, says there are good reasons why parties without leaders tend to increase in popularity.

In a tight leadership race, voters responding to pollsters tend to imagine their favourite candidate winning.

"Even when Canadians know who the likely winner is going to be, there is no real focus on that person until the leadership race is over," Nanos says.

That makes the current Liberals "a very easy parking space" for voters upset with the ruling Conservatives, or unimpressed with the New Democrats in opposition.

As for the traditionally short honeymoons for incoming Liberal leaders, Nanos says the Harper Conservatives have shown repeatedly that "they are very well prepared to welcome them."

Translation: Whomever wins the Liberal leadership will be treated to an onslaught of attack ads — possibly by both the Conservatives and NDP — all designed to publicly and permanently define the new leader in the worst possible terms.

Call it killing the honeymoon.

The fight on the left

What's more, when it comes to the new Liberal leader, the NDP may well be even more ferocious than Harper's notorious attack dogs.

Nanos polling shows the NDP has been steadily losing support to the Liberals in seat-rich Ontario, a critical electoral battleground for both parties.

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NDP Leader Tom Mulcair: who do you think is going to take on Stephen Harper? (Reuters)

"You know the NDP have to have a strategy to challenge the new Liberal leader," Nanos says. "Not which one can be prime minister, but who can best challenge Stephen Harper."

The view from the Conservative benches also anticipates a parliamentary prize fight in the coming months between NDP leader Tom Mulcair and the new Liberal boss.

One Conservative strategist says: "Once Trudeau is installed, he and the Liberals will recognize the obvious if they haven't already — that the Liberal route to office goes through the NDP, not through us.

"They have to kill the NDP as the natural alternative government. And Mulcair's not stupid, he has been doing everything to establish the NDP as that natural alternative."

While the NDP and Liberals are warming up for what could be a bloody fight, the Conservatives seem notably sanguine about slipping a half-dozen points in the polls and having the Liberals nipping at their heels.

"There's a little bit of a doldrums thing going on," says the Conservative strategist.

"Harper has always been best with a script, and right now the government is kind of between scripts.

"It is approaching the mid-point in its four-year term and has done most of what it said it was going to do. Now we have a federal budget coming up, and fiscally there's not much room to manoeuvre."

The strategist says the Conservatives remain confident in the strength of Harper against the opposition leadership, but no one is dismissing what's happening on Trudeau's campaign, either.

"When he's pulling 500 people into a rally in small-town Ontario, and the local Liberals say they don't recognize half the people there, there's something going on."

Pollster Nanos says that while the Liberals are no doubt enjoying the latest poll results, they shouldn't get too carried away.

"Lets face it: They've been in an infomercial for the past few months."

And who really watches those?