Lise Thibault's request was rejected in Quebec Superior Court on Monday.
She had argued that the civil suit could prejudice her criminal trial and should be put off.
She is being sued by the Quebec government for $92,000, at the same time that she faces fraud charges over allegedly illegitimate expense claims.
Thibault hopes to argue before the Supreme Court of Canada that she should have legal immunity as a representative of the Queen.
The country's high court has not said whether it will hear her case.