Progressive Conservative Brian Pallister says accusations that Selinger's team struck a deal with a firefighters union to support him call the results into question.
Pallister also says some delegates to the convention last weekend had their fees covered by the candidates.
He suggests that may have been an unfair inducement to get votes.
Pallister says officials at NDP headquarters should review complaints and determine whether the vote was fair.
Selinger eked out a second-ballot victory over second-place finisher Theresa Oswald by winning 51 per cent of the vote.
Some paramedics have said Selinger secured important votes from the firefighters union by promising to help them in a dispute with paramedics. Booth Selinger's team and the firefighters union deny any deal was made.
Pallister admits that, as an outsider, his call for a review may not hold much sway with New Democrats, but he believes the air must be cleared.
"The NDP has an opportunity here to set the record straight," he said Friday.
"If it believes the process was perfect — and it decides to say that — that's the decision it has to take. But the concerns I'm hearing from Manitobans ... are very real."
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