He was not sitting as an MNA when he was selected as the party's new leader in the Action démocratique du Québec leadership election on October 18, 2009.
While Taillon focussed on issues sensitive to the education system, he was among several candidates in favor of abolishing school boards across the province and giving the responsibility to municipalities.
[7][8] Taillon lost his bid for election in Chapleau, finishing in third place behind the victorious Liberal, Marc Carrière, and Parti Québécois candidate Yves Morin.
Later reports also revealed that the party president, who was supposed to be neutral in the race, helped raise money and organize for Taillon.
Following the narrow victory, Taillon named a new shadow cabinet that did not include a critic's role for his leadership rival, Caire.
Caire later resigned from the party to sit as an independent MNA, joined by caucus colleague and supporter Marc Picard.