Former cabinet minister Peter MacKay says he will not run for leadership of the Conservative Party of Canada.

"After much soul searching, advice from trusted friends, and weighing of the impact on my young family, I have decided not to seek the leadership of the party," the Nova Scotia native said in a release late Monday afternoon.

"I choose not to run at this time for some of the same reasons I stated when I chose not to seek re-election last year. My family is my number 1 priority."

MacKay and his wife, Nazanin Afshin-Jam, have two young children, Kian, 3, and Valentia, 11 months.

MacKay said in the release that he considered a leadership bid over the summer months but ultimately decided to step aside to allow others to run.

"In fairness to others declared, and those in consideration, I feel it is time to decide so as not to negatively impact others," he said.

MacKay led the Progressive Conservative Party before its merger with the Canadian Alliance in 2003. He stepped aside to allow Stephen Harper, former leader of the Alliance party, to run against contenders Belinda Stronach and Tony Clement for leadership of the newly united party.

Former Progressive Conservative leader Peter MacKay shakes hands with then-Canadian Alliance leader Stephen Harper after their announcement of a merger in October 2003. (Jim Young/Reuters)

MacKay was first elected as an MP in 1997 representing the rural Nova Scotia riding of Pictou–Antigonish–Guysborough. He did not run in the last election campaign and now works as a lawyer in Toronto.

"While the opportunity is exciting and the reward compelling, I feel it would be asking too much of them to jump back into politics right now and the heat of a leadership campaign with all that it entails," MacKay wrote. "I know the demands and time away from home that it requires."

MacKay's riding, renamed Central Nova, was ultimately won by Liberal MP Sean Fraser. The former PC stronghold was also held by his father, Elmer MacKay, who served as a cabinet minister in the Mulroney era.

Other top Tories considering bids

The decision comes in advance of the Conservative Party's caucus retreat in Halifax this week, when other top contenders are expected to make their leadership intentions known.

"I am full of admiration for those who will seek the leadership and I stand ready to work with whoever the new leader will be. I am optimistic about the future of the Conservative Party of Canada," MacKay said.

He is the latest high-profile former cabinet member from the Harper government to decide against running for the leadership.

Jason Kenney announced earlier this summer he would instead seek the leadership of the Alberta Progressive Conservative Party in a bid to unite it with the Wildrose Party. Former B.C. MP James Moore also ruled out a run for leadership of the federal party, citing family.

So far, MPs Maxime Bernier, Michael Chong, Tony Clement, Kellie Leitch and Deepak Obhrai have officially registered as candidates for the race to replace Harper.

Others, including former cabinet ministers Lisa Raitt and Erin O'Toole, have shown interest in running for the top job.

"I have made a decision," Raitt told CBC News last week. "The debates are approaching. Everyone needs to know who is involved and who is not involved. And I'm cognizant of people wanting to get on with their lives. So I will put them out of their misery fairly quickly."

There will be five party-sanctioned debates in total, with the first scheduled for November 10 in Saskatoon. The second, a bilingual debate, will be on December 6 in Moncton.