Labour's support for deep sea oil and gas exploration on principle had more potential of dividing the party than the Dunedin community, University of Otago political scientist Bryce Edwards says.
Labour leader David Cunliffe said the party supported the exploration but would pass laws to toughen environmental protection.
However, Labour would not immediately halt existing exploration programmes such as Texan company Anadarko's exploration of the Taranaki and Canterbury basins. The company is soon to start exploration off the Otago coast.
Dr Edwards said the announcement by Mr Cunliffe left two polarising positions: National, which strongly favoured deep sea oil and gas exploration with less concern about environmental protection; and the Green Party which was totally opposed.
Labour now sat somewhere in the middle, favouring the exploration but wanting tighter controls.
''Labour is feeding into how the public is feeling about offshore exploration. The majority are in favour, with the caveat of 'if it is safe'.''
The Labour stance would increase the difference between Labour and the Greens and give the Greens some space to criticise Labour without jeopardising a possible future coalition, he said.
The Greens would not push Labour into a corner on the issue.
The genetic engineering (GE) issue in 2002 caused a major split between the two parties. Green supporters later realised the GE bottom-line policy was a mistake of the past that should not be repeated.
The last 20 years of politics had been devoid of ''bit issues politics'', such as banning nuclear ships, which was a litmus test before most people found themselves opposing the visits, Dr Edwards said.
Labour was founded from coal miners and extraction workers reliant on exploration for their income. It was looking again to attract to those voters.
''Labour activists will be uncomfortable and this has the potential to split the party more than the community.
''Ships doing exploration drilling off our coast will be a test for the community and the left. Labour has traditionally been favourable to mining and extraction industries.
''The environmentalists will be disappointed by the policy,'' he said.