Liberal Party posters were posted overnight Tuesday into Wednesday in the Louis-Hébert electoral district of the Quebec City area, announcing a by-election for Oct. 2.

Premier Philippe Couillard has not yet formally announced the date of the Louis-Hébert by-election.

Some of the posters feature Liberal candidate Éric Tétreault along with Couillard and the slogan ‘La voix économique d'ici' or 'The Economic Voice Here.'

Tétreault will be challenged by CAQ candidate Normand Sauvageau, a retired businessperson.

The Parti Québécois presented its candidate -- Norman Beauregard, a biologist who has spent his career in public service – Monday.

Lawyer Guillaume Boivin will serve as the Québec solidaire candidate, the party confirmed on Wednesday morning. He ran for the party in Louis-Hébert in 2012 and in La Peltrie in 2007 and 2008.

The electoral seat in Louis-Hébert has been left vacant since April when Liberal MNA Sam Hamad resigned. Hamad had served as MNA there since 2003. In 2014, Hamad won easily with 49.22 per cent of the vote, with about 8,000 votes more than his CAQ rival Mario Asselin.