WINNIPEG -- One of the people trying to unseat Manitoba Premier Greg Selinger is appealing a ruling that has given one union a huge block of delegates for the NDP leadership vote.

Theresa Oswald's campaign filed an appeal with NDP headquarters Tuesday over the party's decision to allot 288 delegates -- about 13 per cent of the total votes -- to CUPE Manitoba.

The move came one day after CUPE Manitoba endorsed Selinger, but an Oswald campaign supporter said Oswald was not prompted by anything other than a desire to have the rules followed.

"If the rules are interpreted in a way that advantages one campaign over the other two, it would be normal for those other two to protest," said Rob Hilliard, a former head of the Manitoba Federation of Labour who endorsed Oswald last week.

The NDP allots delegates to the leadership vote based on the memberships of unions, constituency associations, the party's youth wing and other groups. Unions get four delegates for their first 100 members and one additional delegate for each 100 members thereafter.

To qualify, unions must be formally affiliated with the federal New Democratic Party. The Oswald campaign, in a letter signed by Hilliard and two other former labour leaders, says none of the dozens of CUPE locals across the province is affiliated with the federal NDP.

"As we speak, there are zero CUPE locals affiliated with the NDP right now," Hilliard said.

Hilliard said CUPE Manitoba -- the umbrella group for all locals -- is affiliated and entitled to one delegate as a labour organization.

Calls for comment to CUPE were not immediately returned and a spokesman for the NDP said the party would not make any statement.

The leadership contest was sparked by a caucus revolt led in part by Oswald, a former minister of jobs and the economy and, before that, health. Steve Ashton, another former cabinet minister who was not part of the revolt, has also thrown his hat in the ring.

Unions are expected to account for more than 25 per cent of the votes to be cast March 8, although the NDP was still finalizing numbers Tuesday.

While CUPE has endorsed Selinger, other unions such as the United Food and Commercial Workers and United Fire Fighters of Winnipeg have yet to publicly back any candidate.

Hilliard said the Oswald camp is suggesting a two-week deadline for CUPE locals across the province to become formal affiliates of the federal NDP and thereby qualify for delegate status.

The Oswald campaign has asked for a hearing, but had not received a reply from party headquarters.