Two candidates in the upcoming by-election in the riding of Louis-Hebert have dropped out of the race.

The Liberal candidate to replace Sam Hamad, Eric Tetrault, withdrew his candidacy on Wednesday evening following allegations of sexual harassment.

Tetrault was director of public affairs at the mining firm ArcelorMittal in 2014 when he was accused of harassing several female co-workers.

He was the subject of an internal investigation but no formal complaint was filed following its completion.

Premier Philippe Couillard says the Liberals are starting the campaign from scratch and that several candidates have expressed interest in running for the by-election. He defended the party's vetting process, noting that not all documents are available such as the one that ultimately proved to be Tetrault's downfall.

Meanwhile Normand Sauvageau, who who was running for the Coalition Avenir Quebec, said he was dropping out after receiving a call from a reporter earlier in the day regarding his early retirement in 2016.

"I realized at that point just how essential it is for a candidate in an election to be open," he said in a statement.

"More than a year ago, after a 39-year career, I retired in difficult circumstances in terms of labour relations. When I filed my candidacy, I did not tell the Coalition about important facts surrounding my departure."

There are reports that Sauvageau, who worked for ScotiaBank, was the subject of multiple complaints about his behaviour.

With a report from The Canadian Press