GATINEAU, Que. -- Stephen Harper is off and running -- and Tom Mulcair is right behind him.

The NDP leader kicked off his party's election campaign -- the "Campaign for Change" -- across the river from Parliament Hill just moments after his Conservative rival asked Governor General David Johnson to dissolve Parliament.

I believe that governing is about priorities," Mulcair said from an outdoor balcony in Gatineau, Que., overlooking the Ottawa River, the iconic Peace Tower looming in the distance.

"Mr. Harper's priority is to spend millions of dollars on self-serving government advertising and an early election call. My priority is to invest in affordable, quality child care to help families and the economy."

He then proceeded to rattle off a number of areas in which the NDP accuses the Conservatives of falling dramatically short of what Canadians expect from their government, and how New Democrats would do better.

On everything from protecting and restoring the environment and providing fair treatment to Canada's Aboriginal Peoples to creating jobs and doing away with political corruption, the NDP is the better choice, Mulcair said.

"In each of the last three elections, Conservatives have been convicted of wrongdoing. Some of been sent to jail. One-third of the Senate is under police investigation. I believe this must change once and for all."

Mulcair, who did not mention Liberal Leader Justin Trudeau during his speech, also took aim at Harper on the economy. The party's "number 1 priority" will be to "kick-start the economy and get Canadians back to work," he said.

"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 economy has shrunk in each of the last five months and many are claiming that Canada is already in another recession ... clearly, Mr. Harper, your plan isn't working. "

The Conservatives have also gutted Canada's environmental protections and embarrassed the country on the climate-change file, he added.

"My priority is to strengthen and enforce environment rules here at home and have Canada do its part in tackling climate change on the world stage."

Mulcair, whose popularity in recent public opinion polls suggests all three main parties have a shot at forming a government after Oct. 19, said he is focused on doing exactly that.

In 2011, New Democrats achieved historic electoral success, thanks largely to gains made in Quebec under the leadership of Mulcair's predecessor, Jack Layton.

Political observers say the NDP's greatest challenge will be to translate its current levels of support into more seats in the House of Commons.

Some of the main planks of the NDP platform include a promise to create a million $15-a-day child care spaces across Canada and a $15 minimum wage.