Conservative leadership hopeful Lisa Raitt is calling on the party to expel any leadership candidate caught cheating and to impose hefty fines on their campaigns.

There have been allegations in recent days of alleged vote-rigging and membership fraud by people connected to the campaign teams of perceived frontrunners Maxime Bernier and Kevin O'Leary. Both leaders have denied knowledge of vote-buying.

"I am calling for the expulsion of any candidate found to have broken the leadership rules and a significant fine for any campaign found to have authorized this type of activity," Ms. Raitt said in a statement Monday. "These allegations show we need to rethink this process to ensure every new membership is validated by a third party audit."

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Ms. Raitt said the party must begin a rigorous review of all memberships to ensure the leadership race is being conducted fairly.

"Cheaters and rule breakers who do this discourage the involvement of both our long standing and new party members. It makes a mockery of their commitments and corrupts the process." Ms. Raitt said . "We cannot let our legitimate party be impacted by this type of behavior.

Read more: Tories uncover fraudulent members after O'Leary warns of vote-rigging

A sworn affidavit provided to The Globe and Mail alleges that one of Mr. O'Leary's key organizers in the Sikh-Canadian community in Brampton, Ont., offered to pay for party membership – a clear breach of party rules.

The affidavit is being used by leadership candidate Maxime Bernier's camp to target the reality-TV star as a hypocrite after the O'Leary team accused his Quebec rival of committing mass membership fraud last week.

Six Sikh-Canadians swore an affidavit on Sunday alleging that the president of the Conservative Brampton East Riding Association offered to pay for their memberships.

Party rules require membership to be purchased by an individual using either personal cheques or personal credit cards.

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"I was approached by Ron Chatha from the Kevin O'Leary team to provide names and addresses for myself and friends, so they could sign up for the Conservative Party of Canada [and] not to worry about the fees as they will take care of it. But I discussed with my friends, they said they had to pay for the membership so we decided not [to] sign for membership," the six men said in the signed affidavit.

The Sikh-Canadians went to a notary's office in Brampton on Sunday to have their allegations notarized. The affidavit was provided to The Globe from the Bernier camp.

"It is very disturbing and doubly disturbing that Mr. O'Leary was so keen to throw stones at other campaigns, yet he was very clearly in a glass house," Conservative MP Tony Clement, a senior adviser to the Bernier campaign, told The Globe. "This is the height of hypocrisy and it illustrates that his campaign is up to no good."

But Mr. Chatha, who is a key organizer for Mr. O'Leary, flatly denied he engaged in voter buying and accused the Bernier campaign of seeking revenge.

"They tried to recruit me and I refused. Now I am being targeted," Mr. Chatha said. "I haven't even signed anyone. I just signed my family."

The O'Leary campaign released its own statement Sunday evening: "We are disappointed that the whistleblower who brought to light the issue of vote buying is being harassed for doing the right thing. Mr. Chatha has not submitted any lists or memberships in bulk to the O'Leary campaign, and has only signed up his family. The O'Leary campaign will continue to operate with transparency and by the rules."

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Mr. Chatha said he was the one who first complained to party headquarters about false memberships when he looked at the recent list of 278 new members in his riding. Many of the people on that list did not even know they had been signed, he told The Globe.

"I was the one who complained. There is no merit in this. I didn't do anything," he said.

A party official confirmed that Mr. Chatha had flagged suspicious memberships that lead to an investigation and the removal of more than 1,300 people from the party rolls on Friday.

But Mr. Clement fired back that Mr. Chatha is "just trying to cover his tracks," saying the six individuals were not inventing what had transpired.

One of the men who signed the affidavit, Uminder Singh, said Mr. Chatha approached him at a party event a few weeks ago.

"He asked us to sign up as members and we were to pay $10 for the membership but we said we don't want to pay any extra money so he said, 'Fine, sign the membership forms' and he said he would take care of this himself," Mr. Singh said.

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Another man who signed the affidavit, Satnam Singh, also said that Mr. Chatha approached him at a party event.

"Me and my friend said we didn't have the money to pay so he just told us, 'You just fill out the application form and don't worry about the money, we will do it ourselves,'" he said. "I thought it was kind of forbidden so that is why me and my friend rejected."

A third man, Jaskaran Singh, said that Mr. Chatha told him "just to sign [membership] and don't worry about the money and he would pay and take care of us."

The tit-for-tat accusations are a sign of growing tensions between the two perceived front-runners for the Conservative leadership as the Bernier and O'Leary organizations fight it out to sign up as many new members as possible before the March 28 cutoff.

Mr. O'Leary's team fired the first salvo of voter fraud last Thursday when his team said they had uncovered a large number of cases of people in the Tamil-Canadian community in Toronto being signed up without their knowledge. They alleged that untraceable prepaid credit cards were being used to sign up members involving a Tamil-Canadian connected to the Bernier campaign.

Mr. Bernier denied his campaign was involved in vote buying and lashed out at Mr. O'Leary as a "loser."

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The Conservative Party investigated the complaint and found 1,351 members were purchased through two IP addresses that were not paid by each individual as required under the rules. Those memberships were cancelled.

Party spokesman Cory Hann said it wasn't possible to determine which leadership campaign or campaigns were behind the vote-rigging scheme because the memberships were purchased anonymously through the Conservative party website.

Mr. Hann said the party would look into the Bernier camp's accusations against Mr. O'Leary's team but stressed the party is being rigorous in reviewing all memberships purchased during the leadership race.

"If someone has proof to point to we are obviously going to look at it just like we did with the memberships bought at the two IP addresses," he said. "We do regular reviews of memberships and that includes calling members and asking them whether they purchased the memberships on their own."