Supporters of Liberal leadership candidate Brian Gallant say they are not comfortable with anti-shale gas activists becoming temporary Liberal Party members in order to vote for another candidate in the race.

Members of Hampton Water First, a group that opposes the development of a shale gas industry in the province, are urging fellow environmentalists to join the party by the Sept. 26 deadline, so they can vote for Michael Murphy, the former health minister.

They say it's simply a one-day strategic vote because Murphy — who has promised to impose a moratorium on shale gas exploration and a public inquiry into the industry within 30 days of becoming premier — has the best position on the issue.

Denis Landry, the Liberal MLA for Centre-Péninsule-Saint-Sauveur, says he wants people to join the party for a long time. (Liberal Party)

But Denis Landry, the Liberal MLA for Centre-Péninsule-Saint-Sauveur, says short-term members aren't good for a party that is trying to renew itself.

"You only need to be a supporter of the Liberal Party for one day. This is what I have a serious problem with," said Landry.

"I want Liberals to be Liberals for more than one day, for the future of the party.

"I'm supporting this party because I am a Liberal first of all," he said.

"I would like to see the Liberals be there for a long time, not only one day. And I think when you're asking people for support for only one day, you're a bit desperate."

But it is the activists, not Murphy, who have suggested they will join the party only long enough to vote for Murphy.

Murphy has also said his goal, if he becomes leader, will be to persuade environmentalists to remain Liberals for the long term.

The third leadership candidate, Nick Duivenvoorden, has said the activists may be putting all of their eggs in one basket by assuming Murphy would be the most electable Liberal leader in 2014.

The Liberals elect their new leader on Oct. 27 in Moncton.