Cadman's biographer, Tom Zytaruk, says Harper met with the Independent MP in early April 2005 for one hour, according to a leaked version of the manuscript of Like A Rock: The Chuck Cadman Story.
Zytaruk doesn't say what was discussed at that meeting.
The prime minister's office said Tuesday that it was a personal visit to see how the ailing MP was doing. But it's also clear that Harper, as then-Opposition leader, knew Cadman's vote could be crucial in bringing down the governing Liberals over the sponsorship issue.
Several weeks after the Harper meeting, two top party officials visited Cadman in an effort to convince him to rejoin the Conservatives - a visit that is now at the heart of a controversy over allegations that Cadman was offered a $1-million life insurance policy in exchange for his vote.
The Tories have been ambiguous about how many meetings were held with Cadman ahead of their efforts to bring down the Liberal government in the spring of 2005.
MP James Moore has said that there were several chance meetings with Cadman that spring. The party has also confirmed that the two senior operatives met with Cadman on May 19 just before a confidence vote.
Cadman died of cancer two months after voting to keep Paul Martin's Liberal government alive for a few more months.
Harper has denied the Cadman family's claim that Cadman believed he was being offered the insurance policy by the Tories shortly before he died of cancer in exchange for his pivotal vote.
But a tape from 2005 that surfaced last week, has Harper saying he knew an "offer" of "financial considerations" was allegedly made to Cadman.
Cadman's public statements before his death were contradictory, suggesting in some televised interviews that he was offered nothing beyond an unfettered opportunity to run as a Conservative in the B.C. riding of Surrey. In another interview on CKNW radio, he suggested other considerations were offered but doesn't specify them.
The April 1, 2005 meeting with Harper would have come at the height of the Liberal sponsorship scandal. The testimony of former advertising executive Jean Brault - a key player in the sponsorship scandal - began appearing on U.S. blogs on April 2, 2005.
By the time Justice John Gomery lifted the ban, much of Brault's testimony was readily available online.
"Brault's revelations caused popular support for the Liberals to plunge and a confidence vote in the House seemed inevitable," Zytaruk writes. "The Conservatives went into a feeding frenzy."
The meeting with Harper was one of a number of meetings between Cadman and members of the Conservatives and Liberals in the weeks leading up to a historic showdown in the Commons.
The book says two local Tories and John Reynolds - then a prominent Conservative from British Columbia and a key Harper adviser - urged Cadman to rejoin his former party.
The Tories continued to dodge a number of questions Tuesday about the Cadman affair.
Neither the Prime Minister's Office nor a Conservative party spokesman has explicitly denied that two of Harper's close confidants - Doug Finley and Tom Flanagan - made the offer on the eve of a crucial confidence vote.
Finley and Flanagan also didn't reply to questions e-mailed to them.
That left Moore to tell the House of Commons that party officials only offered to take Cadman back into the fold of his former party.
"The only offer made to Chuck Cadman was made by Doug Finley and Tom Flanagan on May 19, 2005, where we talked about Chuck Cadman rejoining the Conservative caucus and running as a Conservative candidate," he said.
But in Zytaruk's book, Cadman's widow says two Tory operatives offered her dying husband the life-insurance policy. Dona Cadman later said she considered it a bribe.
And she maintained in a statement released Monday that party officials made the offer, which she chalked up to "the overzealous indiscretion of a couple of individuals."
But she said Harper convinced her more than two years ago that he knew nothing about an alleged offer.
Cadman's daughter, Jodi, and his son-in-law, Holland Miller, have corroborated Dona Cadman's story.
The Liberals again turned their questions in the Commons - which were largely more pointed Tuesday than during the previous three question periods - to the Cadman affair.
Harper and Moore both insisted Conservative officials only offered to take Cadman back into the party.
The Liberals have asked the RCMP to investigate the issue, and all three opposition parties initially asked the Commons ethics committee to look into the matter.
But New Democrat MP and ethics committee member Pat Martin told reporters outside the Commons Tuesday he would torpedo a committee investigation since he holds the swing vote.
While some have suggested the NDP isn't keen to probe an issue they don't see as politically advantageous, Martin insisted that was a "jaded" interpretation.
"If we did interview the key principle witnesses, they would be protected by parliamentary privilege and nothing we learn could be used against them in a subsequent proceeding," he said.
"So we don't want any of the key actors to be able to hide behind the apron strings of parliamentary privilege."
The NDP have asked Justice Minister Rob Nicholson to refer any investigation to the director of public prosecutions, an independent office created under the Accountability Act.
Liberal MP Sukh Dhaliwal said it's not clear if an investigation would fall under the jurisdiction of the special federal prosecutor.
The Conservatives have not yet explained why they first denied any offer had been made, only to later say a repayable loan was offered to Cadman's local riding association to cover campaign expenses if he rejoined the party.
Repeated appeals to the Prime Minister's Office since the Chuck Cadman affair surfaced have failed to yield direct answers to the following questions:
1. Did anyone from the Conservative party, or connected to the Tories, offer Cadman a $1-million life insurance policy?
- Refused to directly answer the question. Tory MP James Moore has repeatedly said officials only offered to take Cadman back into the party.
2. What did Stephen Harper mean when he said in a 2005 interview that "an offer" that included "financial considerations" was made to Cadman?
- Conservative party spokesman Ryan Sparrow said Monday the offer Cadman mentioned in a TV interview was a repayable loan to the local riding association.
3. If Tory officials Tom Flanagan and Doug Finley offered a repayable loan, what was the amount and what were the terms of repayment?
- No answer.
4. Why did the Prime Minister's Office and the Conservatives first deny an offer had been made to Cadman, only to later say a repayable loan was offered?
- No answer.
5. Why didn't Harper reveal last week that he told Dona Cadman more than two years ago that he didn't know about the alleged life-insurance offer?
- No answer.
6. What motivation would Dona Cadman, a Tory candidate in her husband's former riding, have to fabricate a story about the life-insurance offer?
- No answer.
