On August 13, 2007, Marois announced her candidacy for the riding of Charlevoix, after the incumbent, Rosaire Bertrand, retired from politics after 13 years as the MNA. The by-election was held on September 24, 2007. Marois did not compete against a candidate from the minority governing Liberal party, which chose not to present an opposing candidate, but did face Action démocratique du Québec candidate Conrad Harvey, who had been a candidate in the same riding against Bertrand in the 2007 general elections, and won with 58.2% of the popular vote.