Earlier this month, Harper seemed unequivocal in his defence of Wallin, who has racked up travel expenses of $321,000 since September 2010. He appeared to suggest he'd personally reviewed Wallin's expenses and concluded they're comparable to those of other parliamentarians from Saskatchewan.
"In terms of Sen. Wallin, I have looked at the numbers," Harper told the House of Commons two weeks ago.
"Her travel costs are comparable to any parliamentarian travelling from that particular area of the country over that period of time."
On Tuesday, however, Harper was much more circumspect when NDP Leader Tom Mulcair reminded him that he'd "personally reviewed" Wallin's file and found no problems.
"We have been very clear, as has the Senate and all senators," Harper said, avoiding even a mention of Wallin's name.
"They are reviewing all of their expenses to ensure not only that the expenses are appropriate but the rules in the future for governing such expenses are appropriate. That is a commitment that has been made on this side."
Moreover, Harper's communications director Andrew MacDougall told The Canadian Press that the prime minister never intended to suggest he'd personally reviewed or approved Wallin's expenses.
"I don't believe the PM said he'd personally reviewed her expenses," MacDougall said in an email.
"He was referencing the fact that the total amount of Senator Wallin's expenses was comparable to other parliamentarians from Saskatchewan."
In fact, the expenses in question racked up by Wallin were listed as "other travel," presumably to places other than Saskatchewan, the province she was appointed to represent. Over the same period, she claimed only $29,423 in travel to the province.
Wallin has said Senate accounting rules count only direct flights between Ottawa and a senator's home province as regular travel. She has said she often flies to Saskatchewan from Toronto, where she owns a condo, or from other parts of the country, which is counted as "other travel."
Until now, Wallin has also insisted that "no offer of repayment was made or asked for" with respect to her travel claims.
However, her office did not deny a CTV report Tuesday that she actually paid back a "substantial" amount before meeting two weeks ago with an external auditor who had been asked by the Senate's internal economy committee to examine Wallin's travel expenses.
"No comment," was all Wallin's office would say.
NDP ethics critic Charlie Angus said Harper is distancing himself from Wallin now that it appears there may have been something wrong with her expenses.
Harper's initial defence left the impression "there was nothing to see, move along, I've looked at this and it's fine," Angus said in an interview.
"I think they circled the wagons around Pamela Wallin two weeks ago and decided to dig in. Now the wheels are falling off ... so they seem to be trying to distance the prime minister."
Wallin is one of a number of senators whose expense claims have come under scrutiny recently. Questions have also been raised about her eligibility to sit in the Senate since her primary residence appears to be in Ontario, not Saskatchewan.
The Constitution stipulates that a senator must reside in the province he or she was appointed to represent. It does not define what is meant by residency.
Wallin has said that last year she spent 168 days in Saskatchewan, where she owns several properties.
An external auditor is also examining the claims of three senators — Conservatives Mike Duffy and Patrick Brazeau and Liberal Mac Harb — for a $22,000 annual housing allowance meant to compensate senators who keep a secondary residence in the National Capital Region.
An unknown number of other senators, who could not provide documentary proof of their primary residence, are being interviewed by a sub-committee of the internal economy committee.
Duffy, a longtime Ottawa resident who had claimed his cottage in Prince Edward Island as his primary residence, last week volunteered to repay his housing allowance.
Although Conservative and Liberal leaders in the Senate have promised to make the results of the various probes public, no one is revealing as yet how much Duffy or Wallin has repaid or the names of all the senators being questioned.
In the Commons on Tuesday, New Democrats demanded that the government lift the veil of secrecy on what Angus dubbed the "Senate rip-off."
"When will the government come clean with taxpayers and call on the Conservative-dominated Senate to tell us how many times has (Wallin) been investigated, how much money has she had to pay back and what are the consequences to be for her ripping off the taxpayer?" said Angus.
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