Marjory LeBreton is not given to second guessing, and the Conservative senator isn't about to start now.

It was LeBreton who, as government leader in the Senate, introduced the motion last year to summon the auditor general to probe the expenses of every senator.

It was a response to crisis emanating from the investigations into the spending habits of retired Liberal senator Mac Harb and suspended Conservative senators Patrick Brazeau, Mike Duffy and Pamela Wallin.

All but Wallin now face criminal charges.

LeBreton acknowledges it's been a painful process for everyone, but it had to be done.

"It's been very difficult for some senators, it's been very difficult for the institution," she says in an interview in her Parliament Hill office about what she hopes will come out of the review.

'I think the public has a distorted view of what the Senate does.' —Conservative Senator Marjory LeBreton

"At the end of the day, as painful as it's been, I think the Senate will be more credible and it will still be seen to lack legitimacy because it's an appointed body."

And that's the rub, says Stephen Azzi, a professor at Carleton University's graduate program in political management.

"This will not solve the Senate's problems. The Senate's problems are much more fundamental… it has to do with the Senate being unelected and unaccountable and clearing up concerns over expenses isn't going to solve that problem."

What the auditor general is after

Few Senators will talk publicly about the audits, in large part because the auditor general demanded they sign a letter drafted by his office committing to keeping the audits confidential.

But there's a clear pattern to what Ferguson's staff want. Multiple senators say they have been asked to substantiate where, when and why they travelled and told to produce airline tickets, taxi chits and letters confirming an invitation to speak at an event.

It is, says Independent Liberal Senator George Baker, exactly what the Senate asked Ferguson to do.

"I mean the Senate asked, unanimously, for a complete audit of the Senate. Not just the administration, but of every individual senator and every single expenditure relating to that senator."

Still, many senators are concerned that they will be found to have violated the rules, and like Duffy, Wallin and Brazeau, ordered to repay money spent doing what they thought senators should do: promoting charitable causes, educating the public on what senators do, attending partisan political events.

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Auditor General Michael Ferguson is conducting an audit of Senate expenses. Multiple senators say they have been asked to substantiate where, when and why they travelled and told to produce airline tickets, taxi chits and letters confirming an invitation to speak at an event. (Adrian Wyld/Canadian Press)

A number of them complained that the auditor general is too narrowly defining the role of Senate business and has failed to recognize the political role senators historically played.

LeBreton's heard it, too.

"I think the public has a distorted view of what the Senate does. The Senate does some very important work but, unfortunately, it's only the bad headlines that get attention."

What about MPs?

There's also a concern that when Ferguson releases his final report either later this year or early in 2015, the media will focus only on who else might be found to have broken Senate spending rules.

Baker sees another outcome.

He's confident that the Senate audit will force MPs to open their books, too, after years of resistance. His rationale: the public will demand it, especially now that a precedent has been set by the Senate to invite that kind of accountability for how taxpayers' money is spent.

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Conservative Senator Marjory LeBreton drafted the motion to call in the auditor general. She says the audits will help the Senate's credibility, to a point. (Sean Kilpatrick/Canadian Press)

"I think it is now politically impossible for MPs to claim an exemption from the Auditor General's Act simply because it has now been established by the Senate of Canada… that every single expenditure be audited."

Ferguson made a similar case last November during an appearance before the procedure and House affairs committee, offering to do the job himself.

"I believe that independent audits and some form of oversight would strengthen members' accountability and enhance the public's confidence in the governance mechanisms of the House of Commons," he told committee members.

MPs have yet to take him up on the offer. The Commons rejected a bid by Green Party Leader Elizabeth May to take a look at their books. Many opponents argue there's no need, since voters get to hold them accountable every election.

Accountable, yes. But it's a far cry from the transparency now being brought to how senators spend taxpayers' money — or proposed, by Ferguson himself, for the Commons.

Watch Chris Hall's full piece from CBC News' The National.