The party says there are 12,238 people signed up to be eligible for delegate selection for the March 8 vote during the NDP's annual convention.
That's an increase of more than 5,500 from November, before the leadership race was called.
But it's below the 14,000 total for the last race in 2009.
Theresa Oswald has said her camp has brought in about 1,000 new members, while Steve Ashton says his team signed up 600 people in Thompson alone.
Premier Greg Selinger, who is running to keep his job, called for the leadership vote after a caucus revolt late last year.
The party now has to determine how many members are in each of the province's 57 constituencies and assign each constituency a corresponding numbers of delegates.
The three candidates — Oswald, Selinger and Ashton — will then try to have delegates who support them elected at constituency meetings scheduled for February.
Ashton predicts a close leadership race, with a second ballot needed to determine a winner.
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