Sen. David Tkachuk, Conservative chair of the Senate's internal economy committee, says the Deloitte audit "most probably" won't be done before senators break for the summer on June 28.
While his committee can receive Deloitte's final report at any time, it can't be released until it's been tabled in the Senate.
That raises the awkward prospect of the committee having to keep the eagerly anticipated and potentially explosive Wallin report under wraps until the Senate resumes sitting in mid-September.
However, Tkachuk says the committee will ask the Senate clerk at a meeting Tuesday if there's some way to release the report when it's received, even if the upper chamber isn't sitting.
"I don't think we can table it in the Senate but maybe we don't have to," Tkachuk said in an interview.
"We may find a way around that."
Deloitte has been examining Wallin's travel expenses since December, initially focusing on the period from September 2010 to November 2012. During that time, she claimed only $29,423 in what's deemed "regular travel" between the national capital and her home province of Saskatchewan, and an eye-popping $321,000 in "other travel" elsewhere in Canada and abroad.
Wallin, who has condos in Toronto and New York, has said her "other travel" expenses are distorted because they include indirect flights in which she stopped over in another city before continuing on to Saskatchewan.
The internal economy committee had hoped the Wallin audit would be done at the same time as audits into the housing allowances and living expenses of three other senators — Mike Duffy, Patrick Brazeau and Mac Harb — which were released last month.
However, Deloitte asked for more time to examine Wallin's travel expenses "because they wanted to go back another year" to 2009, Tkachuk said.
The committee has invited Deloitte auditors to provide an update on their progress at a meeting Thursday.
"I think all we want is an update as to when it will be complete and that's basically it. They're not going to talk about the audit, that's for sure," Tkachuk said.
The timing of the Wallin audit presents a dilemma for members of the internal economy committee, which oversees the administration and finances of the Senate.
On one hand, Tkachuk said it's a long-standing rule that all senators must be given the right to see any report, through tabling in the Senate, before it's released publicly. To do otherwise is "disrespectful of senators."
"We have to follow due process. I know all the media's very excited but, you know, I don't exist to supply stories for the media," he said.
That said, given the media and public interest, Tkachuk acknowledged there's a good chance details of the Wallin report will inevitably leak out if the committee tries to sit on it for a couple of months until the Senate resumes business.
"It's not fair to the person who's being audited because it's being leaked out, it's not being tabled in the Senate where there's opportunity for debate and discussion," he said.
Leaks of partial details can be distorted and, thus, particularly unfair, he added.
Bits and pieces of Wallin's file have already been leaked, including the fact she has already reimbursed the Senate for $38,000 in improperly claimed travel expenses. Tkachuk said reports that she's been asked to repay another $20,000 are "false."
He also dismissed as false suggestions that Deloitte is digging deeper into Duffy's expenses.
"There's a lot of things being said everywhere, many of them not true."
On Thursday, Liberal Sen. Percy Downe told the Senate that, by his calculation, the chamber has spent $240,000 so far to audit the expenses of Wallin, Duffy, Brazeau and Harb. The final bill will be higher, Downe maintained, because Deloitte is continuing to scrutinize the expenses of Wallin and Duffy.
However, Tkachuk said Deloitte has not been asked to revisit Duffy's expenses.
After initially administering a gentle slap on the wrist to Duffy, who claimed to have repaid all his housing and living expenses, the internal economy committee last week asked the RCMP to investigate the matter.
The move followed news that Prime Minister Stephen Harper's chief of staff, Nigel Wright, had personally footed the $90,000 bill for Duffy to repay his invalid expense claims. Wright resigned five days later.