The Liberals contend that Pierre Duchesne was biased in his reports before his resignation last month.
Duchesne worked at Radio-Canada for 25 years and was most recently the network's chief correspondent at the legislature in Quebec City.
Duchesne defended his integrity at a news conference on Friday, saying the Liberal complaint is nothing more than intimidation.
"I think it's not an ethical complaint," he said. "It's a political complaint. It's ... intimidation. It's a new game actually and that's part of the story."
He says the Liberals shouldn't have waited until after his departure from Radio-Canada to complain about his alleged lack of objectivity.
Duchesne says he only decided to run for the PQ within the last 10 days and that there was no contact with the party while he was still employed by Radio-Canada.
His candidacy was announced on Thursday by PQ Leader Pauline Marois, who defended him in the wake of questions about his integrity by Premier Jean Charest.
Marois insisted Duchesne had not shown any favouritism to the PQ while he was a TV reporter.
Duchesne will run in Borduas, a riding near Montreal that is currently held by former PQ member Pierre Curzi. Curzi quit the party in 2011 to sit as an Independent and has announced he is not running again.
Charest's mandate does not run out until next year but there has been increasing speculation that he will call an election for this fall.