Stephen Harper has begun the mid-summer marathon that will be longest federal election campaign in recent history.

Harper emerged from Rideau Hall Sunday morning, confirming he had asked Gov. Gen. David Johnston to dissolve Parliament for a general election to be held Monday, Oct. 19.

Speaking after his meeting with Johnston, Harper emphasized the need for a strong hand on the economy and issues of security, including the "violent global jihadist movement" represented by ISIS.

Canada's Prime Minister Stephen Harper speaks to reporter after asking Governor General David Johnston on Sunday to dissolve Parliament.

"Canadians will make a critical decision about the direction of our country, a decision with real consequences, a decision about who has the proven experience today to keep our economy strong and our country safe," Harper said.

"This is no time for risky plans that could harm our future," he added.

"It is time to stay the course and stick to our plan," Harper said.

Pressed by reporters why he launched the campaign so far in advance of the fixed election date, which boosts the cost to taxpayers, Harper said: "Everybody knows the election date and the campaigns of the other parties, as near as I can tell, have already begun."

"I feel very strongly...that those campaigns need to be conducted under the rules of the law. That the money come from the parties themselves, not from government resources, parliamentary resources or taxpayer resources."

"In terms of the advantages this party has, in terms of the fact that we're a better financed political party, a better organized political party, and better supported by Canadians — those advantages exist whether we call this campaign or not.

"What we do by calling this campaign is making sure that we are all operating within the rules and not using taxpayers' money directly."

After his visit to Rideau Hall, Harper headed to Montreal for a rally in the riding of Mount Royal, stopping on the way at a bakery in the Ottawa suburb of Orléans, where incumbent Conservative Royal Galipeau faces a challenge from high-profile Liberal candidate Andrew Leslie.

Police arrest a protester prior to a rally for Conservative Leader Stephen Harper in Montreal Sunday. (Christinne Muschi/Reuters)

A group of protesters were waiting outside Harper's event at Montreal's Ben Weider Jewish Community Centre chanting anti-Harper slogans. One was led away by Montreal police officers, and was heard by CBC News to say "I was joking, there is no bomb." Police then cordoned off the sidewalk and asked demonstrators to remain on the other side.

Inside, Harper gave his first stump speech of the campaign, touching on his now-familiar themes of national security and sound economic management. He dismissed both Mulcair and Trudeau as not being up to the challenges ahead.

The friendly, partisan crowd chanted "majority."

'Clear choice'

Speaking in Gatineau, Que., NDP Leader Tom Mulcair also stressed the economy as a defining issue of the campaign.

"Canadians have a clear choice," he said. "Four more years of Mr. Harper and the Conservatives or my plan for change."

"We will kick-start the economy and get Canadians back to work. This is our number one priority," he said.

'Canadians have a clear choice. Four more years of Mr. Harper and the Conservatives, or my plan for change' 9:08

"Wages are falling, incomes are stagnant and household debt is skyrocketing ... middle class families are working harder than ever but can't get ahead," Mulcair said.

The NDP leader also used his speech to introduce himself to Canadians who may not know him, stressing his upbringing, his values and his years in politics.

Unlike Harper, Mulcair did not take any questions from reporters.

Most recent polls have shown Mulcair and the NDP leading or in a virtual tie with Harper and the Conservatives.

Liberal Party Leader Justin Trudeau launched his campaign in Vancouver, where he aimed his pitch at middle-class voters.

"If people want change in this country, it is because the economy is not working for them," he said.

'I believe a prime minister has 3 main jobs - keep the country united, keep Canadians safe, and give everyone, the Canadian people, a real and fair chance to succeed' 21:50

Trudeau also used his speech to take swings at both Harper and Mulcair, saying Harper's plan had "failed" and Mulcair's is a "mirage."

"You want change that works for you," Trudeau said.

Costing 'tens of millions' more

Green Party Leader Elizabeth May, speaking in her British Columbia riding of Saanich—Gulf Islands, chastised Harper for the length of the campaign.

"What isn't right is to claim that the taxpayers aren't subsidizing this election. It's going to cost Canadians tens of millions of dollars more," she said.

Gilles Duceppe, the leader of the Bloc Québécois, spoke in Montreal, saying he was struck by the number of young people who have joined the party.

"I want to help those young people to play their role," he said.

Mulcair spent the afternoon in Ottawa, attending the funeral of former Progressive Conservative cabinet minister Flora MacDonald.

Liberal Leader Justin Trudeau marched in Vancouver's Pride parade on Sunday, keeping a promise he said he made to organizers despite the early election call. (Donna Lee/CBC)

Trudeau marched in Vancouver's Pride parade, keeping a promise he made to organizers that he'd attend.

"No one's going to get me to break my word, particularly not Stephen Harper," he said, firing back at critics who wondered about him travelling West Sunday morning and making his opening statement later than the other leaders.

Voters will get their first chance to see the party leaders together in action on Aug. 6 during a debate hosted by Maclean's magazine in Toronto.

Historic length

The election campaign, which will last 11 weeks, or 78 days, will be one of the longest in the country's history.

According to The Canadian Press, only Canada's first two election campaigns were longer. The 1867 campaign lasted 81 days, while the 1872 campaign went for 96 days. Back then, voting was staggered over the country for a period of several months.

The longest race in recent history was a 74-day campaign back in 1926.

A long campaign is seen as benefiting the Conservatives, who are acknowledged to have the biggest war chest.

During a typical 37-day election period, each party can spend a maximum of $25 million. For each additional day, that limit is increased by 1/37th, or an extra $675,000, meaning an 11-week campaign would allow parties to spend more than $50 million.

Individual candidates also get an additional $2,700 a day to add to their usual limit of approximately $100,000.

A longer campaign will also cost Canadian taxpayers more. By Elections Canada's estimate, a traditional five-week, 35-day campaign costs about $375 million to run. Parties are also reimbursed for half the money they spend during an election campaign.

Green leader says her party is ready 14:28

The Conservatives under Harper are seeking a fourth consecutive mandate, while Mulcair and Trudeau are both entering their first federal election campaigns as the leaders of their respective parties.

As Harper and Mulcair both highlighted, the management of the economy will be a key campaign issue.

Canadian economic growth has stumbled in recent months. Statistics Canada reported Friday that the total value of the country's economy declined by 0.2 per cent in May, the fifth consecutive monthly slide.

More seats up for grabs

At the dissolution of Parliament, the Conservatives held 159 of the 308 seats in the House of Commons, compared with the NDP's 95 and the Liberal Party's 36.

The Bloc Québécois, the Forces et Démocratie party and the Green Party had two seats each. There were also eight independent MPs and four vacant seats.

'Stephen Harper has decided to call an election. We all know that it's because he wants to give himself an advantage using public funds' 9:57

However, there are more seats up for grabs this time round. Following the release of 2011 census population numbers, federal electoral boundaries were revised, which led to an increase in the number of seats in the Commons to 338.

The new ridings are located in:

Ontario: 15 more seats (121 seats in total).

British Columbia: 6 more seats (42 seats in total).

Alberta: 6 more seats (34 seats in total).

Quebec: 3 more seats (78 seats in total).

The seat total in all the other provinces and the territories remains unchanged.