For Peter MacKay, the next Conservative Party leader doesn't necessarily need to be a political outsider.

But he or she has to be a "very substantive and serious" person who brings life experience and thoughtful policies to the party, says the former cabinet minister, who is leaving the door open to running himself.

"It looks better to have that kind of heft, as opposed to reality-TV, Kardashian-style of politics," Mr. MacKay said in an interview with The Globe and Mail.

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And is a "substantive" person in direct contrast to Prime Minister Justin Trudeau?

"People will have to come to their own conclusions about that," he said.

The federal Conservatives are set to pick their new leader in May, 2017, as part of the fallout from their election loss in October and Stephen Harper's resignation.

The Nova Scotia-born Mr. MacKay, who didn't run in the last election, is seen as a popular choice among Red Tories and his name repeatedly comes up as the front-runner in leadership polls.

Although no formal announcements have been made, other potential leadership contenders include Conservative MPs Kellie Leitch, Jason Kenney and Maxime Bernier, and even Kevin O'Leary of TV's Shark Tank – although the latter also said he'd consider a run for the Liberals.

Now a partner in the Toronto office of U.S.-based global law firm Baker & McKenzie, Mr. MacKay takes the subway to work and says he is "quite happy" with his new life outside of politics, focusing more on his young family with wife Nazanin Afshin-Jam.

But he says he's being encouraged by some within the party to run.

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"I haven't ruled it out," Mr. MacKay said, sipping Earl Grey tea in a boardroom at his firm's Bay Street office overlooking Lake Ontario.

"But am I pining away, thinking about it and organizing and getting an apparatus in place? Uh, no. I've done that before," he said, referring to his run for the Progressive Conservative leadership in 2003 before it merged with Mr. Harper's Canadian Alliance to form the modern Conservative Party of Canada.

"It's a tremendous commitment."

These days, Mr. MacKay refers to himself as another type of PC – a "practical Conservative."

When asked why he doesn't just say no to a leadership run, Mr. MacKay answered: "I'm still interested and engaged in a lot of issues that I care about, and politics is a vehicle to bring about change. It sounds trite, but it's true."

Although he hasn't been to Ottawa since the election, Mr. MacKay has been following politics. He says he is concerned with the swift changes Mr. Trudeau's government is making.

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He accused the Liberals of "spending a disproportionate amount of time undoing the things that we did."

He mentioned Liberal pledges such as the return of the long-form census, rolling back Old Age Security eligibility to 65, reviewing the temporary foreign workers program and changing Canada's child benefit payments.

"It just seems almost a policy announcement a day. And they're back – Canada's back – haven't you heard?" Mr. MacKay said, repeating Mr. Trudeau's line.

"That, to me, is ludicrous."

He pointed to the Canadian Forces' 10-year involvement in Afghanistan as an accomplishment under the Conservative government that is now being pushed aside by Mr. Trudeau. Canada was not absent on the world stage during the Conservative rule, he said.

"That's partisan in the extreme, that kind of statement. It suggests somehow that only Liberals are Canadian," Mr. MacKay said.

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"It comes across very much as, 'We're entitled. We're supposed to be the governing party.'"

But Mr. MacKay acknowledges that Mr. Trudeau's "positive message" resonated during the election campaign – and has been taken up by Conservative Interim Leader Rona Ambrose.

"She's hit the right note on a lot of the issues," he said.

During his 18 years in office, Mr. MacKay served as minister of foreign affairs, defence and justice. It was a career that came with its share of controversies, both personal and professional: He faced intense criticism for taking a military helicopter from a private fishing trip in Newfoundland to a news conference on the government's dime; he also had a failed public romance with former Conservative MP and floor-crosser Belinda Stronach.

He also repeatedly made the political Hill Times newspaper's list of "sexiest male MPs" – a designation Mr. MacKay says "mortified" him.

"It's sort of like being picked best-looking in a leper colony," he said, dryly.

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In his last post as justice minister, Mr. MacKay, a former Crown prosecutor who speaks often on the rights of victims, publicly clashed with the judiciary on a number of occasions.

Mr. MacKay said some judges "castigated" Conservative laws, including a refusal to implement the mandatory victims surcharge, a fine for offenders.

"We still have judges that are bristling – those filthy, democratically elected people telling us what to do. It's rather shocking when you think about it," Mr. MacKay said.

"I'm startled that there was such push-back."

But he denies being behind some of the more contentious Conservative laws, such as a ban on face coverings at citizenship ceremonies. "I wasn't the engineer, let's say, of things like niqab legislation," he said.

Asked whether he still talks to Mr. Harper, Mr. MacKay said: "I haven't regularly; put it that way."

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He said the former prime minister, like most leaders, had a "sense of destiny" when he decided to run in the last election after almost a decade on the job.

"It's like prize fighting," Mr. MacKay said.

"If you stay in the ring too long, somebody will knock you out. That's just a proven fact. You're tempting the odds."