AJAX, Ont. -- One day into his re-election campaign and Stephen Harper had already turned his main political rivals into a two-headed nightmare: "Justin and Mulcair."

The Conservative leader repeated that moniker several times Monday in reference to the Liberal leader with the famous last name and the NDP leader who used to be Thomas, now just Tom.

The strategy is simple: the more indistinguishable the voters find the Liberals and the New Democrats, the more likely they are to split the anti-Tory vote and let the prime minister sail smoothly up the middle.

At the same time, of course, Harper needs to set himself apart in what by all accounts is shaping up -- at least in the early days -- to be a cramped, three-way race.

"Justin and Mulcair and all of their people have voted against the GST cut -- they have voted against every single tax cut and family benefit that we have brought in as a government," Harper told a rally of about 100 party supporters at a Greek restaurant in Kingston, Ont.

"Let Justin and Mulcair explain their carbon tax, carbon-price schemes. We Conservatives will stand for responsible, environmental regulation that doesn't come at the expense of jobs and our economy.

"Let the other guys explain their plans for drug-injection sites in your neighbourhoods, for legalized marijuana and legalized prostitution, for ending mandatory prison sentences for even the most violent criminals and for bringing back the ineffective and wasteful long-gun registry."

Conservative campaign spokesman Kory Teneycke said Monday there's no grand plan behind the new nickname. They're just the two guys the Tories happen to be running against, he said.

The Conservatives refer to Trudeau by his first name -- in speeches, in attack ads -- because that's how the Liberals branded him, and that's how Canadians know him, he added.

"The public views him as a celebrity and celebrities have one name: Oprah, Beyonce, Bono, Justin," Teneycke said in an interview en route to an evening rally in Ajax, Ont.

Since the start of the campaign, Harper has also started to direct more and more criticism at Mulcair, whose popularity has been on the rise, according to recent polls. Until recently, Trudeau spent years as the Tories' No. 1 target.

Harper warned supporters in Kingston that the NDP's "high-tax, high-spending, high-debt ideology would wreck our economy."

The Tory leader focused on the economy Monday by trying to reassure Canadians, insisting that hurdles like the sliding price of crude oil have caused only momentary ripples in some sectors.

Right out of the campaign's starting gate, the Tories have been trying to sell Harper's reputation as a strong fiscal manager.

But for months, economic indicators have told a different story: the economy contracted the first five months of 2015 and forecasters -- including the Bank of Canada -- have downgraded their economic predictions for the year.

Despite the dampened expectations, analysts have projected some growth over the rest of 2015 -- forecasts Harper has been talking up since the campaign began Sunday.

"Look, these are temporary effects," Harper said earlier Monday as he started the day in Laval, Que., north of Montreal.

"We all knew that with lower oil prices, lower resource prices, there were going to be some temporary effects in some sectors of the economy."

He said Canada remains "head and shoulders" above its G7 partners in terms of long-term economic growth, including on the job front.

He also promised a re-elected Conservative government would spend $60 million a year on increased and extended tax credits for businesses that hire tradespeople.

Some sectors of the Canadian economy are still growing, Harper argued, despite what he described as the outside factors that are to blame for the slowdown.

He pointed a finger -- as he has in the past -- at the instability in China and Europe as well as the unexpected slow growth in the United States.

"Even through that, we have sectors of the economy that continue to grow," Harper said. "We remain optimistic about the turnaround that everybody is predicting."

One expert said it's hard to fact check whether Harper's statements on the Canada's economic growth has been stronger than other G7 countries because he didn't specify a time frame.

Stephen Gordon, an economics professor at Quebec City's Laval University, said in interview that without specifics, Harper's statement sounds more like "very vague and fuzzy, feel-good things."

Gordon said it's also difficult to know just how temporary the current obstacles will be.

On the bright side, he said the U.S. recovery appears to have taken hold and the low Canadian dollar should help boost exports.

However, Gordon said, nobody knows what will happen to the price of many resources, which make up a big segment of the economy.