OTTAWA — A three-person Senate committee investigating the housing-allowance claims of senators faces a task so daunting that experts suggest it’s time to call in Canada’s auditor general.

A Postmedia News review of Senate expense claims shows that only seven of Canada’s 104 senators (one seat is currently empty) have not claimed any sort of housing allowance since 2011. That means the three-member committee conducting the probe will have to interview about 50 of its peers to determine whether their claims are legitimate.

The remaining 40 or so senators have made claims for hotel rooms, not residences, when they stay in the national capital for Senate business.

Under the rules, the housing allowance, used for a secondary residence in Ottawa, can be claimed only by senators whose primary home is more than 100 kilometres from the capital.

“The issue here is integrity of public finances,” said Donald Savoie, a parliamentary and governance expert from the University of Moncton who has written numerous books about government.

“The solution is turn everything over to an auditor. The auditor generalwould be a good candidate to ensure integrity in the country’s finances.”

David Tkachuk, who heads the Senate’s internal economy committee, told Postmedia News he would not be discussing how the three-person committee will go about its work. Questions sent to Tkachuk, Sen. George Furey and Sen. Carolyn Stewart Olsen, who are conducting the review, were not answered Wednesday.

The auditor general does have the right to examine senator expenses – if the Senate itself agrees. In 2010, it decided to give the auditor general limited access to expense reports, and last year the results were released.

Auditor General Michael Ferguson wrote in his June 2012 reportthat of seven housing allowance claims examined in the review, auditors found “insufficient evidence” to determine whether the Senate administration had ensured two claimants complied with the policy. And of 24 living expense claims, which can include claims for hotel accommodations and food, explanations were provided for 23 of the claims but one had no explanation at all.

Lack of documentation was also cited in four of the 36 travel claims examined, leading Ferguson to question the “honour principle” under which senators operate. “Because some of the expense claim files do not always contain sufficient documentation, it is difficult for the Administration to clearly conclude that expenses are appropriate,” he wrote.

“The fundamental question is can the Senate be trusted to be investigate itself?” NDP Leader Thomas Mulcair asked Wednesday. “The public has a right to know what’s happening with this body, but I don’t think we’re ever going to get a straight answer. That’s the real problem.”

Currently, it is up to Senate staff and the members of the Senate’s internal economy committee to flag and review any suspicious expense claims, including housing allowances, which can top out at a maximum $21,000 a year. Much like doctors, teachers or lawyers, parliamentarians are self-governing, punishing rule violators, but referring criminal issues to the RCMP.

The House of Commons has declared seats vacant before when it found an MP in violation of the rules, and the Senate has equal power to turf one of its own.

“(The Senate) is a self-governing society, like a lot of professions,” said parliamentary expert Ned Franksfrom Queen’s University in Ontario. “It would be wrong to say that parliamentarians are only in it for themselves. They care for their institution, they care for their party, they care for their country.”

Every year, senators declaring whether their primary residence is within 100 kilometres of the capital and swear a statement about it. A similar type of oath is required for obtaining an Ontario health card: that form requires a signatory to declare they “intend to continue making Ontario my primary place of residence.”

“When a senator is appointed, they go to a series of meeting and I can assure you the law clerk … is the one that impressing upon them that they must own property in that province and be residents of that province” (to claim an allowance for a secondary residence in Ottawa), said retired senator Sharon Carstairs, from Manitoba. “That is done for every single senator so nobody can say they’ve never been informed of that.”

During her 17 years as a senator, Carstairs said, “To my knowledge, no one was blatantly breaking the rules.”

Preliminary results should be available by March from an independent audit looking into the housing allowance claims made by Sen. Mike Duffy, Sen. Mac Harb, and Sen. Patrick Brazeau.

On Friday, the internal economy committee announced it had referred the housing declarations of Duffy, Harb and Brazeau to auditing firm Deloitte for review, and has sought special legal advice on the question of Duffy’s residency. Sen. Pamela Wallin has said she met with auditors and submitted all documents requested.

The internal economy committee asked every senator to submit a copy of their income tax return, showing their address, a copy of their health card, driver’s licence and a statement as to where they vote municipally, provincially and federally. Those forms were requested in December and the majority of senators have fulfilled that request.

The process has been kept relatively private, but the review has cast a cloud over the entire Senate chamber, which finds itself increasingly inundated with calls for its abolition.

“It’s a crisis for those who sit in the Senate because it makes them feel so bloody uncomfortable,” Carstairs said. “This kind of thing, I can tell you, makes them cringe. They probably don’t want to be there this week.”

The seven current senators who have not claimed the allowance are Sen. Marjory LeBreton, Sen. Vernon White, Sen. Pierre De Bané, Sen. Colin Kenny, Sen. Marie-P. Poulin-Charette, Sen. Anne Cools and Sen. Jim Munson, according to the Senate’spublicly available quarterly expense reports. (Sen. Doug Finley didn’t claim the allowance for six months in 2011 and six months in 2012, according to expense records.)

It’s not clear how long it will take to interview the remaining senators who own or rent properties in Ottawa, and no timeline has been publicly placed on when a final report from the Senate’s internal economy will be tabled.

“There’s enough pressure on the Senate, enough concern in the Senate that it will be done pretty quickly,” Franks said. “It’s a really messy thing.”