Dembélé became a member of Adéma-PASJ's executive committee in 2004, and he served as Director-General of Geology and Mines from 2005 to 2010. On 10 April 2013, he was designated as Adéma-PASJ's candidate for the July 2013 presidential election. Party leader Dioncounda Traoré was Adéma-PASJ's original candidate for the vote when it was first scheduled to be held, in 2012, but in the wake of the March 2012 coup d'état he was allowed by the ruling junta to take up the post of interim President, and he consequently agreed not to stand as a presidential candidate.