After a stunning election night victory, Justin Trudeau said his majority Liberal government is proof that 鈥減ositive, optimistic鈥 politics are not just a 鈥渘aive dream.鈥

Trudeau said Canadians chose 鈥渞eal change鈥 when they elected Liberal MPs across the nation, pushing out the Conservative government after nearly 10 years and forcing Stephen Harper to resign as party leader.

鈥淪unny ways my friends, sunny ways,鈥 Trudeau told a jubilant crowd in his Montreal riding of Papineau, invoking the philosophy of former prime minister Wilfrid Laurier.

鈥淚 didn鈥檛 make history tonight, you did,鈥 Trudeau said, addressing all Canadians. 鈥淎nd don鈥檛 let anyone tell you any differently.鈥

Harper did not announce his resignation in his concession speech Monday night, but the president of the Conservative Party issued a statement saying he has been instructed to 鈥渞each out to the newly instructed parliamentary caucus to appoint an interim leader.鈥

It was not immediately clear whether Harper would stay on as MP for Calgary Heritage.

The Liberals are celebrating a historic victory after leaping from third place directly to the seat of power. As of 2 a.m. ET Tuesday, the Liberals were elected or leading in 185 ridings. With 100 seats, the Conservatives were reduced to Official Opposition status. The NDP were leading or elected in 42 ridings, the Bloc Quebecois had 10, and the Green Party had one.

Trudeau, 43, is following in the footsteps of his late father Pierre Elliott Trudeau, and establishing Canada鈥檚 first political family dynasty.

On several occasions throughout the marathon, 78-day election campaign, Trudeau fondly mentioned his father, who served as prime minister for 16 years. But political observers say it鈥檚 not just the Trudeau name that helped the Liberals regain power after a humiliating slide in the 2011 federal election.

Trudeau, billing himself and the Liberals as the only path to 鈥渞eal change,鈥 was able to convince voters across the country that he was ready to lead the country -- despite what the attack ads claimed.

Addressing his stunned supporters in Calgary Monday night, Harper said he had 鈥渁n unbelievable honour鈥 to serve as Canada鈥檚 prime minister.

鈥淲e gave everything we have to give and we have no regrets whatsoever,鈥 he said.

鈥淲hile tonight's result is certainly not the one we had hoped for, the people are never wrong,鈥 Harper said, adding that the Tories will form a 鈥渟trong鈥 Official Opposition.

鈥淭he disappointment you also feel is my responsibility and mine alone,鈥 he told the crowd.

The political future of NDP Leader Thomas Mulcair was also uncertain Monday night as the party slid into third place. Under its late leader Jack Layton in 2011, the NDP surged to Official Opposition status, thanks to major gains in Quebec.

But in the final weeks of this election campaign, the New Democrats began losing support in the province.

Addressing a crowd in his Quebec riding of Outremont, Mulcair did not say whether he would stay on as leader, but promised that the NDP will continue its work on health care and economic policies.

鈥淐anadians have asked us all to work for them. We will not let them down.鈥

Mulcair also said he spoke with Trudeau and congratulated him on his 鈥渆xceptional achievement.鈥 He added that Canadians have rejected 10 鈥渓ong years鈥 of Harper鈥檚 rule and a 鈥減olicy of fear and division.鈥

Some have attributed the NDP鈥檚 downfall in Quebec to Mulcair鈥檚 position that women should have a right to wear face-covering veils at citizenship ceremonies. Polls have shown strong support for niqab bans in the province.

The niqab debate was one of the unexpected flashpoints on the campaign trail, with Harper saying that a re-elected Conservative government would re-introduce and adopt banning niqabs and other face coverings at citizenship ceremonies.

Harper鈥檚 rivals and critics called his insistence on a niqab ban an attempt to demonize Canadian Muslims, as well as distract voters from real election issues.

Trudeau said the Liberals would not push for such a ban. He campaigned on tax breaks for the middle class, which he said would be paid for by raising taxes on the wealthiest one per cent.

He also promised a new, tax-free child benefit to replace the Conservatives鈥 universal child benefit and drew ridicule from Harper when he said he would run three 鈥渕odest鈥 deficits to boost the economy and invest in infrastructure projects.

The Liberal win did not come as a surprise to anyone who has been following the last few weeks of the election campaign.

Heading into election day, Nanos Research put the Liberals in the lead, at least nine points ahead of the Conservatives.

Peter MacKay, the former Conservative minister who did not run for re-election, said it was painful to watch the Conservative losses Monday night.

His own Nova Scotia riding of Central Nova, considered a Tory stronghold, was claimed by Liberal candidate Sean Fraser.

鈥淥bviously not the results were hoping for across Canada,鈥 MacKay told 麻豆影视 earlier Monday night.

Former Conservative prime minister Brian Mulroney congratulated Trudeau on his win Monday, but said he felt 鈥渟adness鈥 for the Tories who were defeated after doing 鈥渁 lot of good work for Canada.鈥

Mulroney said that 鈥渟easons change鈥 and political tides come and go.

鈥淭hat鈥檚 what democracy is all about and we鈥檝e seen it tonight,鈥 he told 麻豆影视 Anchor and Senior Editor Lisa LaFlamme.

鈥淚 ran and was successful because I wasn鈥檛 Pierre Trudeau. Jean Chretien ran and was successful because he wasn鈥檛 Brian Mulroney and Justin Trudeau tonight was successful because he wasn鈥檛 Stephen Harper.鈥

Mulroney said he warned the Conservatives early on in the campaign that they shouldn鈥檛 underestimate Trudeau, who was often derided as an inexperienced candidate with little substance.

鈥淚 felt and I said: be careful鈥e鈥檚 a man of significance,鈥 Mulroney said.

Green Party Leader Elizabeth May told a crowd on Vancouver Island Monday night that she spoke with Trudeau and congratulated him. She held on to her Saanich-Gulf Islands seat.

Bloc Quebecois Leader Gilles Duceppe, meanwhile, was defeated in his riding of Laurier-Sainte-Marie. He lost his seat to the NDP鈥檚 Helene Laverdiere.