The poll projected Conservatives will gain nine seats in Tuesday's election, for a total of 136 of the 308 seats in the House of Commons.
That would still leave the minority government short of the 155 seats it needs to form a majority, forcing Harper to rely on co-operation with other parties to pass legislation.
Under Ekos's projections, the Liberals would lose 11 seats and end up with 84.
Harper was elected with a minority for the first time in January 2006 and managed, by some calculations, to have the longest minority government in Canadian history.
He called the election on September 7 to seek a renewal of his mandate to govern.
Speaking in the town of Cornwall, Prince Edward Island on Monday, Harper said:
"The number one job of the next prime minister of Canada is to protect this country's economy, our earnings, savings and jobs at a time of global economic uncertainty."
"If you give me the honour of re-electing me as your prime minister, I can assure you that I will make it my top priority to protect Canada's economy and Canadians' stake in it," he said.
"The number one job of the next prime minister of Canada is to protect this country's economy"
Stephen Harper, Canada's prime minister
Dion has called on voters to "stop Stephen Harper," saying the prime minister "has no plan" to safeguard Canada's economy from the worldwide problems provoked by a collapse in the US subprime mortgage market.
"We have a plan to create jobs, to ensure that we are doing all we can in these tough economic times to protect our pensions, our savings, our mortgages, and our jobs," he said.
Canada's economy has fared better than that of many of the other Group of Seven (G7) industrialised nations. Unlike the US and the UK, banks in Canada are not in danger of collapse.
However, around 75 per cent of Canadian exports go south to the US and in the past - such as in 1975, 1982 and 1991 - when the United States' economy shrank, so did Canada's.