The poll's findings illustrate Harper's status as a uniquely polarizing figure, with 19 per cent of Canadians surveyed naming him the best head of government in the past five decades, while an equal percentage named him the worst.
Both those numbers rose, as the percentage of people naming him the best leader rose eight points from last year's poll results, while the percentage of those naming him the worst rose one point.
Pierre Trudeau remains the most admired prime minister, named by 36 per cent of respondents as the best. Trudeau has held the top spot since Angus Reid began asking the question in 2007.
Harper jumped past Jean Chretien, at 12 per cent, to take second spot, while simultaneously moving into a tie with Brian Mulroney for the worst.
"The reality is you have these two groups of people who either love Harper or hate him," said Angus Reid vice-president Mario Canseco. "There's a little bit of appreciation for what he's done, but most of that appreciation is coming from the centre-right-minded voter," he said.
Harper's strongest support comes from Alberta and Manitoba/Saskatchewan, with 35 and 31 per cent of respondents from those regions, respectively, naming him the best prime minister.
Twenty-eight per cent of Atlantic Canadians and 24 per cent of Quebecers named Harper the worst prime minister.
Some of Harper's popularity came at the expense of fellow conservative Brian Mulroney, Canseco said. While the percentage of people naming Mulroney the worst prime minster has remained relatively stable, those supporting him as the best prime minster has plummeted from 14 per cent in 2007 to six per cent this year.
The popularity for other long-serving prime ministers has remained relatively stable over time, which Canseco attributes to legacies such as the Bill of Rights and the Constitution left by Trudeau, and the national unity battles fought by Chretien.
"I think the main difficulty for Harper in that sense is there's no clear legacy at this point," Canseco said. "There's no big defining moment for his tenure. "Of course, he's going to have four more years to build one."
The poll of 1,002 Canadians was conducted between Aug. 10 and 11. The margin of error for the poll is estimated to be 3.1 percentage points, 19 times out of 20.
Top prime ministers since 1968 as chosen by Canadians.
Pierre Trudeau - 36 per cent
Stephen Harper - 19 per cent
Jean Chretien - 12 per cent
Brian Mulroney - 6 per cent
Paul Martin - 2 per cent
Joe Clark - 2 per cent
Kim Campbell - 1 per cent
John Turner - 1 per cent
Not sure 22 per cent
Stephen Harper second-best and worst PM since 1968: Poll (external - login to view)