Former Progressive Conservative cabinet minister and Liberal premier of Quebec Jean Charest will not run for the leadership of the Conservative Party of Canada.

"I will not be a candidate. It is final," he told Radio-Canada's Patrice Roy in an interview broadcast this evening on ICI RDI.

Watch the full French language interview with Charest here.

Before Christmas, Charest told RDI that he was thinking of entering the race to succeed Andrew Scheer, who resigned as leader in December after failing to win the October federal election.

"I thought a lot. I consulted and, finally, I made the decision not to be a candidate," he said in French.

"The party has changed," he added. "There are subjects on which, obviously, I have principles, like the environment, but also on social issues, upon which I took positions."

During the federal election, the Liberals managed to weaponize Scheer's past opposition to same-sex marriage and abortion and the fact that he had never marched in a Pride parade — raising doubts in the minds of some Canadians about his commitment to LGBTQ rights.

Many Conservatives argued that the next leader would have to deliver a more moderate message on social issues for the party to be competitive in the next federal election.

Charest said he weighed the impact of a leadership run on his family and his already busy work schedule. He also said that the rules governing the contest played a part in his decision.

"The rules of the leadership race are very strict. Basically, the rules were not written for an outside candidate. The deadlines are very tight, it does not give much time to recruit new members and to set up a national organization," he said in French.

A surprise

Former Conservative cabinet minister and Canadian Alliance leader Stockwell Day said Charest's decision not to run came as a bit of a surprise.

Day said that Charest was in Vancouver on Friday making a presentation at a law firm with which Day is associated. After that presentation, he said, Charest gave every indication that he intended to enter the race.

"There were some very significant people there … and he was quite clear that he was pretty well in," said Day.

"I've heard as recently as today that one of the people that was helping to organize that meeting on Friday actually heard from him and he was still saying he was in. So yeah, I'm a bit surprised."

A shadow over his candidacy

Over his long political career he served in Brian Mulroney's cabinet before taking on the leadership of the federal Progressive Conservatives when they were down to just two seats in the 1990s.

He left the federal scene in 1998 to join the Quebec Liberal Party, eventually serving as premier between 2003 and 2012.

For years now, Quebec's anti-corruption squad, known as UPAC, has been investigating the Quebec Liberal Party's financing during the Charest period.

Sources previously have told Radio-Canada Charest was aware of the shadow that investigation could cast over his candidacy, but the former premier maintains he did nothing wrong.

Stephen Harper

Last week, Charest's lawyer said he is innocent of any wrongdoing in political financing and Quebec's anti-corruption squad should immediately end its six-year investigation, which has not led to charges against Charest's friend, Marc Bibeau, or anyone else.

"Stop this investigation," said Michel Massicotte. "Stop saying we are hiding something, or whatever. We have offered our full co-operation, but this co-operation does not seem to have been reciprocated."

Last week, Maclean's magazine columnist Paul Wells reported that former Conservative prime minister Stephen Harper resigned from the board of the Conservative Fund Canada — the financial arm of the national party — so he could be more actively involved in the upcoming leadership race to succeed Scheer.

The magazine, citing an unnamed source, said Charest sought Harper's endorsement in a December phone call but the former prime minister refused to give it.

Wells said that a Conservative source told him Harper left the board to actively block Charest's leadership bid.