GREENPEACE says 76% of Australians are opposed to the proposed expansion of Abbot Point, a move that would make it the world's largest coal port.
A Galaxy poll commissioned by the environmental group showed 69% of Queensland respondents were against the development.
The poll interviewed 1051 people from various states and territories, including 670 from capital cities, asking them: "Do you support or oppose the approval of the world's biggest coal port in the Great Barrier Reef World Heritage Area?".
Of those randomly interviewed, 190 were from Queensland and the majority were from south-eastern Australia.
Greenpeace senior campaigner John Hepburn said the poll results showed most Australians were against the plan.
"Now it's up to Queensland's leaders to listen to the community and protect the Great Barrier Reef and the tens of thousands of jobs that rely on it," he said.
"We are putting the question to both Anna Bligh and Campbell Newman: Will you put the short-term profits of coal barons ahead of the long-term future of Queenslanders?"
Mr Hepburn said, if approved, Abbot Point would become three times bigger than any other coal port in the world, resulting in more than 4000 ships cutting through the reef each year.
He claimed the development would destroy more than 650 hectares of sea bed.
Earlier this week, the Daily Mercury reported Environment Minister Tony Burke had extended the project's approval deadline to allow more time for impact assessment studies.
North Queensland Bulk Ports Corporation plans to reclaim the sand from Clark Shoal to form a protected harbour with 12 land-backed wharves to accommodate projected medium-term demand for bulk exports and industrial products at Abbot Point.
Stage one is likely to have four berths and a tug facility and stage two could include eight more berths.