The credibility of a key witness in a legal bid to overturn Conservative victories in six closely contested ridings came under fire Monday as hearings began into allegations of voter-suppression tactics during the last federal election.

Eight Canadians — supported by the left-leaning Council of Canadians — are challenging the results in those six ridings, alleging misleading or harassing phone calls kept some people from voting and may have affected the results.

Central to the Federal Court case by eight applicants is a report by the firm of pollster Frank Graves, which he says shows signs of a targeted voter-suppression campaign aimed at non-Conservative voters during the May 2011 election.

Story continues below advertisement

On Monday, Conservative party lawyer Arthur Hamilton grilled Mr. Graves, president of Ekos Research, over donations to the federal Liberals dating back to 2006, as well as inconsistencies in prior court affidavits submitted as part of the case.

Mr. Graves is unfit to be an expert witness in the case, Mr. Hamilton argued.

The Conservative party lawyer produced screen shots from the Elections Canada website showing three donations by Mr. Graves to former Liberal leader Michael Ignatieff and current party chief Bob Rae between 2006 and 2008.

Mr. Graves, who had previously said he did not believe he had ever donated directly to Mr. Ignatieff or Mr. Rae, said his office recorded the cheques as donations to the party.

"They're modest amounts from six, seven years ago, and I honestly don't recall. Nor do I understand the discrepancy for how they appear in our books and how they appear on Elections Canada," he said.

Later, outside the courtroom, Mr. Graves said he was unhappy about Mr. Hamilton's line of questioning.

"I found it a little surprising that he went back to the issue of what was a clerical error in the submission of the affidavit the last time, which was cleared up immediately and clearly. I'm not too happy about that," Mr. Graves said.

Story continues below advertisement

"On the other business, my office thoroughly went through all of our cheques and tax receipts and other information and came up with the right numbers. On our forms, it says, 'Donations to the Liberal party.' Whether they were to the Liberal party or to a specific candidate, I have no idea."

Earlier in the day, Mr. Hamilton argued the case is frivolous, saying the eight applicants are really just stand-ins for the left-wing council.

"There are simply too many pieces of evidence which point to the fact that the Council of Canadians is the real applicant here," Mr. Hamilton told the court.

He told judge Richard Mosley the group stands to benefit financially and politically from the case, regardless of the outcome.

"There is a financial windfall to the Council of Canadians," Mr. Hamilton said. "They are raising money with respect to this application."

Mr. Hamilton is asking the court to dismiss each of the applications. The council has no bona-fide witnesses who could testify that they actually were dissuaded from casting a ballot because of the calls, he noted.

Story continues below advertisement

None of the eight applicants actually failed to vote in the 2011 election as a result of the alleged tactics.

But Garry Neil of the Council of Canadians dismissed the Conservative argument. The applicants need only show the calls were made, therefore sullying the electoral process, and not that anyone was fooled, for the results to be overturned.

The six ridings in question are Vancouver Island North; Yukon; Saskatoon-Rosetown-Biggar; Elmwood-Transcona and Winnipeg South Centre in Manitoba; and Nipissing-Timiskaming in Ontario.

The case is parallel to — and unsupported by — an ongoing Elections Canada investigation into fraudulent robo-calls, stemming from complaints that have surfaced in 56 ridings across the country.

While the misleading phone calls appeared to target non-Conservative voters, the Conservative party insists it had no involvement in any such scheme and says it is assisting the investigation.

A shadowy operative known only as "Pierre Poutine" is believed to be behind the calls. However, Elections Canada has not yet been able to find that person.