Caroline Mulroney, the daughter of former prime minister Brian Mulroney, will run for the Ontario Progressive Conservative leadership — a race that earlier in the day was also joined by former MPP Christine Elliott — sources with knowledge of her intentions told CBC Toronto.

Mulroney has a law degree from New York University and work experience on Wall Street, but has never held elected office and has only rarely faced the media, though she had a quick interview with CBC's Catherine Cullen at last year's federal Conservative leadership convention.

Elliott announced "I'm in" on Twitter on Thursday afternoon, confirming earlier reporting by CBC News. Elliott ran for the party's leadership twice but was defeated by Tim Hudak, and later by Patrick Brown. Brown resigned as leader following allegations of sexual misconduct from two women.

She is currently the province's medical patient ombudsman — a position she was appointed to by Premier Kathleen Wynne. Elliott, who was married to the late Conservative finance minister Jim Flaherty, is also a former deputy leader of the PCs and represented Whitby–Oshawa from 2006 until her resignation in 2015.

Vic Fedeli, the party's finance critic for the last five years, who also represents the northeastern Ontario riding of Nipissing, was chosen by caucus as temporary leader on Jan. 26.

However, he said Tuesday he will not run to be the permanent leader, instead pledging to fix the "rot" in his party.

PC MPP and energy critic Todd Smith, who had indicated he was considering a run, announced Thursday on Facebook that he would not join the race, saying "fees established by the Party executive last night are simply too high."

Under those rules, leadership candidates must submit $100,000 in fees and deposits to run, with another $25,000 due later to access the party's membership list. Each candidate's campaign spending cannot exceed $750,000.

The Power Panel weighs in on Christine Elliott and Caroline Mulroney's entrance into the race. 7:29

Votes will be cast electronically between March 2 and March 8, and the results will be announced March 10. The party's leadership election organizing committee has said the Tories would stick to a one-member, one-vote rule.

Candidates — and any new members — must register with the party by Feb. 16.

Elliott and Mulroney join former Toronto city councillor Doug Ford in the race, who announced his bid on Monday.

On Twitter, Ford welcomed Elliot's decision to run, saying: "I look forward to talking about positive ideas for a stronger [Ontario PC Party] and how we're going to beat [Wynne]."

I’d like to welcome my friend <a href="https://twitter.com/celliottability?ref_src=twsrc%5Etfw">@celliottability</a> to the race. As I said, I respect my opponents. I look forward to talking about positive ideas for a stronger <a href="https://twitter.com/OntarioPCParty?ref_src=twsrc%5Etfw">@OntarioPCParty</a> and how were going to beat <a href="https://twitter.com/Kathleen_Wynne?ref_src=twsrc%5Etfw">@Kathleen_Wynne</a>. <a href="https://twitter.com/hashtag/PCPO?src=hash&ref_src=twsrc%5Etfw">#PCPO</a> <a href="https://twitter.com/hashtag/OnPoli?src=hash&ref_src=twsrc%5Etfw">#OnPoli</a> —@fordnation

Asked how the upheaval in the Opposition would affect the upcoming election, Wynne said what happens with the Tories is outside of her control.

"The Tories will either be energized or depleted by their process, that's up to them," she said.

Regardless of who is chosen as leader, there will be a "strong contrast" between the two parties' policies, she said.