By Scott Haggett and Nia Williams
CALGARY, Alberta (Reuters) - Canada's left-leaning New Democrats ended a 44-year run in office by the Conservatives in the province of Alberta on Tuesday, sweeping to victory on a promise to review oversight of the oil and gas sector in the country's energy heartland.
The election was a seismic political shift in the province and sparked the immediate resignation of Progressive Conservative Premier Jim Prentice as party leader. He also quit his legislative seat.
"We made a little bit of history tonight," New Democrat Premier-elect Rachel Notley told jubilant supporters.
Following a month-long campaign, the New Democratic Party (NDP), which has never held more than 16 seats in the 87-seat provincial legislature, will lead a majority government.
Official results showed the NDP appeared set to win 54 seats while the Progressive Conservatives were likely to take just 10, behind the even more staunchly conservative Wildrose Party, which was on course for 21.
The NDP is expected to be far less accommodative to the Western Canadian province's powerful energy industry, and investors in energy shares on Canadian stock markets were expected to react negatively on Wednesday.
Notley has proposed a review of oil and gas royalties in the resource-rich province and reduced support for some pipeline projects, such as TransCanada Corp.'s controversial Keystone XL project. The NDP had also promised to hike corporate tax rates by 2 percentage points to 12 percent.
Alberta's oil sands are the largest source of U.S. oil imports.
"I think the business community is going to be awfully worried here tomorrow morning," said Jeremy McCrea, analyst at AltaCorp Capital Inc. "There are going to be a lot of worried executives on what royalty rates are going to be here going forward."
Notley moved to assuage worries of the province's oil industry in her acceptance speech, saying her party would be a "good partner" to the energy sector. Notley also said Canada needed a national approach to address environmental issues.
The Canadian Association of Petroleum Producers, the country's most powerful oil lobby, said the new premier should focus on more building more pipelines.
"We do not think now is the time for a royalty review that will add uncertainty at a time when jobs and capital investment are very much at stake," spokesman Jeff Gaulin said.
MISCALCULATION
The Conservatives had won 12 straight elections in Alberta, but support for the rookie premier plunged during the campaign and right-wing voters split support between the Conservatives and the younger, more conservative Wildrose, which appeared on track to be the official opposition.
Prentice, who left investment banking to become party leader in September, had a 75 percent approval rating at the beginning of March. A poll this week showed his approval rating had dropped to 31 percent.
"My contribution to public life is now at an end," Prentice told supporters following the stunning defeat.
Dissatisfaction over Prentice's tax-raising budget, the expense of the early election call when the province faces a C$5 billion ($4.1 billion) budget deficit and a series of gaffes by the conservatives squandered the party's lead.
"This will go down as one of the biggest miscalculations in Canadian political history. He did not have to go early," pollster Bruce Cameron told CBC television.
The historic win by the NDP, running in fourth place just a month ago, was met with disbelief on social media where even NDP supporters appeared stunned by the scale of the victory.
"Pigs must be flying all over Alberta," one user, @canadasean21, tweeted.