The Liberals lost the 1990 provincial election, though Mahoney was re-elected without difficulty and became Chief Opposition Whip. He ran for the leadership of the Ontario Liberal Party in 1992, although he had only a minimal support base within the party. Most political observers believed he was attempting to increase his public profile, to be assured of a cabinet position when the Liberals returned to power. He was generally regarded as being on the right-wing of the party during this campaign.