NDP leadership candidate Dwain Lingenfelter, a former deputy premier, has been considered the front runner in the campaign to succeed Lorne Calvert. (File/CBC)

The Saskatchewan NDP has decided to throw out 1,100 questionable memberships paid for by leadership candidate Dwain Lingenfelter.

The party has also asked a lawyer to investigate how the memberships could have been bought on behalf of people who didn't want them.

The NDP has been reviewing the matter since late last week, when questions were raised about the applications.

Some people in the Meadow Lake area said they were being signed up for NDP memberships without their consent.

Lingenfelter, who said it was a mistake made by an overzealous volunteer, apologized and said he took full responsibility.

The party has arranged to have Swift Current lawyer Robert Hale look into how it happened and how it can be prevented in the future.

Hale is a New Democrat who ran for the party against Brad Wall in the 2007 election but has had no role in any of the leadership campaigns. In addition to Lingenfelter, Deb Higgins, Ryan Meili and Yens Pedersen are in the race to succeed NDP leader Lorne Calvert.

"We just need to do this for Mr. Lingenfelter; we need to do it for Ms. Higgins; we need to do it for Mr. Pedersen; and we need to do it for Ryan Meili," Hale said.

"But mainly, we need to do it for the membership of the New Democratic Party. We need people to feel satisfied that the leadership content committee has done appropriate due diligence on this when they make their decision of what is exactly going to take place."

The party hopes Hale will have his work done as early as next week. It's not yet known whether Hales's findings will be made public, McDonald said.