OTTAWA - The Ontario Progressive Conservatives' efforts to leave behind weeks of unprecedented chaos took a hit Wednesday as candidates vying to replace ousted leader Patrick Brown painted a picture of a toxic party culture rife with allegations of corruption, bullying and electoral fraud.

With a spring election looming, all four candidates squaring off in the final leadership debate in Ottawa vowed to tighten rules around party nominations, combat sexual harassment, and ensure that the voices of the grassroot members are heard.

“We have to address the corruption in our party,” said social conservative advocate Tanya Granic Allen, who is competing alongside former Tory legislator Christine Elliott, Toronto lawyer and businesswoman Caroline Mulroney, and former Toronto city councillor Doug Ford.

Brown's abrupt resignation amid sexual misconduct allegations has exposed cracks in the party's structure, issues with its nomination processes, and discrepancies in its membership numbers. The Tories' interim leader has vowed to “root out the rot” and the party has overturned nominations in two ridings.

Granic Allen, who trails in various polls but has arguably been the most aggressive at the race's two debates, repeatedly asked her competitors if they would reopen nomination contests where there have been allegations of interference and bullying.

“The three of you have stood idly by as the party was run into the ground by Patrick Brown,” she declared.

Ford, who often backed Granic Allen, said he would reopen problematic races and recounted being at nomination meetings where he heard accounts of ballot stuffing.

“I'm going to make sure they're transparent, people are held accountable and there's going to be integrity here,” he said.

Elliott said she would ensure rules were followed for races to be conducted properly, while Mulroney also promised to take action.

“We need to make sure our nomination process is as fair and open and transparent as possible,” she said. “We need to make sure we're as strong as we can be.”

Following heated exchanges on the issue, Elliott, who has nearly a decade of experience as a provincial legislator, eventually called for a focus on the Tories' real enemy - Liberal Premier Kathleen Wynne.

“I think it's really important that we remember why we're all here,” she said. “We all have to come together when this is all over because the star target here is Kathleen Wynne, not each other.”

Elliott received some of the most withering attacks of the night as she was forced to defend her appointment as Ontario' health-care ombudsman under the Liberals, a post she held until jumping into the race.

“People want to know which Christine we're gonna get?” Ford said. “Are they going to get the Christine who wants to replace Kathleen Wynne? Or are we going to get the Christine that took a $220,000 political appointment from Kathleen Wynne?”

Elliott turned to Ford, a long-time family friend, and said she was selected by an independent panel and had nothing to apologize for.

“I am very proud to have served as patient ombudsman,” she said.

Elliott also clashed with Granic Allen over the province's Green Energy Act. Both agreed it should be repealed but Granic Allen went a step further saying she would cancel all green energy contracts awarded by the Liberals.

“I'm going to rip all of those wind turbines out of the ground,” she said.

Elliott, a lawyer, argued tearing up contracts will hurt taxpayers, who will have to foot the bill for legal costs as businesses sue for breach of contract.

“You can't just rip wind turbines out of the ground,” Elliott said. “How are we ever going to get people to invest in Ontario if we don't respect contracts?”

Western University political science professor Cristine de Clercy said Elliott was the strongest performer but suggested her attempts to show party unity may have been overshadowed by some of the debate's nasty attacks.

“Ford and Granic Allen in particular seemed to want to often start airing the party's dirty laundry,” she said. “I think Christine Elliott deliberately tried to move away from that trajectory and also demonstrate she can pull the party together.”

Wilfrid Laurier University political science professor Barry Kay agreed Elliott was the most effective, noting she didn't do anything to directly antagonize supporters in other camps, a key strategy that could help secure more support.

“The safest bet for the Conservatives is Elliott and I think she probably reinforced that image,” he said. “She didn't lose it.”

Ford, whose populist message has resonated with the Tory base, nonetheless tried to cast himself as the candidate with the broadest appeal.

“People coming up to me everywhere we go saying, 'I'm a lifelong NDP, I'm not joining the PC party to be a PC, I'm joining the party because of you.”' he told reporters after the debate. “Everywhere I go. 'I'm a lifelong Liberal, I'm joining the party because of you.”'

All four candidates were also grilled on whether they would allow Brown to run under the Tory banner in the election.

Elliott and Mulroney said they would let the Barrie, Ont., politician back into the fold if he cleared his name of the sexual misconduct and financial impropriety allegations he has denied. Ford said only that Brown “has to take care of a few things.”

Granic Allen was the only one to say unequivocally that Brown would not be welcome under her leadership.

Voting for the leader begins online Friday with the winner announced March 10.