OTTAWA – Justin Trudeau’s Liberal Party has swept into office with a surprise majority, ousting Prime Minister Stephen Harper and capping the biggest comeback election victory in Canadian history.

The Liberals dominated the country’s east coast and Elections Canada results showed them surging in Quebec and Ontario, well above what polls had projected, due in large part to a collapse of the country’s other main opposition party, the New Democrats. The results ended nearly 10 years of Conservative rule. The Canadian Press reported that Harper would resign as leader but stay on as a member of Parliament.

The result is a vindication of Trudeau’s campaign to reject Harper’s budget restraint agenda, claiming the nation needs a return to deficit spending to combat economic woes triggered by an oil-price collapse. Trudeau, 43, also used his youthful optimism to exploit a thirst for change, as almost three- quarters of voters said they were ready to oust Harper’s Conservatives after more than nine years in power.

“What we see so far is a repudiation of the Conservatives under Harper,” said Maxwell Cameron, professor of political science at the University of British Columbia. “Clearly people want change, and they want Harper out, and they’ve decided quite unequivocally that agent of change is Trudeau.”

The Liberals were elected or leading in 189 of the 338 seats in Canada’s House of Commons as of 11:40 p.m. New York time, with the Conservatives on pace to take 103, the NDP 36, 10 for the separatist Bloc Quebecois and one for the Green Party, Elections Canada returns show. All three major broadcasters forecast a Liberal majority.

The Canadian dollar fell after the networks called a Liberal victory, down 0.2 percent to C$1.3043 per U.S. dollar in Toronto, dropping for a third day. The currency has depreciated 10.9 percent against the U.S. dollar this year.

Trudeau’s victory marks one of the biggest political rebounds in Canadian history. The Liberals become the first third-place party to win an election, and the party’s seat gain of 150 is the biggest ever. The Liberals, who governed for about two-thirds of the 100 years before Harper came to power, won just 34 districts in the 2011 election, the worst result in their history.

Every opinion poll in recent days had indicated the Liberals held a firm lead in the race, and were on course for at least a minority victory. While the Conservative vote held relatively stable during the campaign at about 30 percent, Liberal gains came mostly at the expense of Tom Mulcair’s NDP, which held a slim but persistent lead in the opening weeks. Yet Trudeau, whose father rose to power in the first wave of “Trudeaumania” in 1968, was seen by voters as having the best chance of defeating Harper. Trudeau becomes the second-youngest prime minister in Canadian history.

Trudeau’s Liberals swept Canada’s four Atlantic provinces, won both Quebec and Ontario — the two most populous provinces – – and appeared set to capture a seat in Calgary, Harper’s hometown, for the first time since 1968, when Trudeau’s father won his first election.

The NDP, which had 95 seats when the election was called, were on pace to finish with one-third that.

“I’m quite surprised,” said Janet Brown, a Calgary-based independent pollster. “I think we were all prepared for a Liberal minority but what appears to have happened is the NDP vote has really collapsed.”

Trudeau will now seek to pursue his platform including higher infrastructure spending and middle class tax cuts. Those will be financed by budget deficits of about C$25 billion ($19 billion) over three years and tax hikes on workers earning more than C$200,000. He’s also pledged to legalize marijuana, cancel the purchase of F-35 fighters, be more assertive on climate change and abandon the country’s bombing campaign in Syria and Iraq against the Islamic State.

His challenges include reviving an economy buffeted by plunging prices for oil and other commodities. Canada’s economy is forecast to expand just 1.1 percent this year, among the weakest in the Group of Seven, forcing the Bank of Canada to cut interest rates twice this year.

Trudeau also needs to find ways to build new pipeline capacity in the face of opposition from environmentalists, and determine whether the Bank of Canada should target higher inflation. He also needs to manage some of the world’s most expensive real-estate markets that threaten the financial system.