Stephen Harper is now categorically denying the Conservative Party machine was behind misleading robo-calls that confused voters in Guelph and elsewhere, calling the entire matter a "smear campaign" by the NDP and Liberals.
"The Conservative Party can say absolutely and definitely it has no role in this," the Prime Minister told the Commons Wednesday.
He challenged the NDP to produce proof of the misdeeds and send it to Elections Canada.
In the absence of evidence, Mr. Harper said, he thinks this is merely a scorched-earth exercise by parties that lost the spring election.
"Otherwise I think we just conclude this is simply a smear campaign without any basis."
Wednesday was the fifth Question Period where the Tories have fielded allegations they engaged in dirty tricks designed to sway the election. Documents from Elections Canada detailing the watchdog's investigation have shown how detailed the scheme was in one Ontario riding.
The Conservatives appear to be trying to ride out the controversy – blaming it on a rogue operative, even though a former Tory staffer allegedly linked to the Guelph robo-calls has publicly protested his innocence.
Elections Canada alleges in court filings that a political operative hiding behind the alias "Pierre Poutine" engineered an off-the-books scheme using robo-calls and a disposable cellphone to discourage opposition voters from casting ballots the riding of Guelph last May.
Documents retrieved from an Edmonton court detail exactly how Canada's elections watchdog believes someone linked to the Conservative campaign in the Southwestern Ontario riding tried to suppress the vote for rival candidates on May 2, 2011.
This comes as opposition parties accuse the Tories of election misdeeds across a broader array of ridings – about 30 to 40 throughout the country.
"The Conservative Party had nothing to do with these inappropriate phone calls," Mr. Harper said.
It was only Monday the Tories had to withdraw such a similarly categorical pronouncement – on an entirely different topic.
On Friday, Foreign Affairs Minister John Baird squarely accused the NDP of behind a Twitter account that was attacking Public Safety Minister Vic Toews.
On Monday however the Liberals admitted it was one of their own behind Vikileaks30. They acknowledged research staffer Adam Carroll was behind the Twitter account that broadcast personal details from court filings on the breakdown of Mr. Toews's marriage.
NDP MP Pat Martin pointed out in the Commons Wednesday that one of Mr. Harper's cabinet ministers recently publicly suggested former Tory aide Michael Sona was the culprit in the Guelph robo-call case.
On Tuesday however Mr. Sona released a statement declaring himself innocent of the matter.
"Canadians want their government to fix health care, not elections," Mr. Martin said.
"The kid they threw under the bus now says he didn't do it. Who's the new fall guy and how far up the food chain does this treachery go?"
MPs are immune from criminal or civil legal action for what they say in the Commons.