The government's leader in the Senate says the Senate should be abolished if it can't be reformed, comments that come as Prime Minister Stephen Harper returns this week to Ottawa, where he is expected to face questions about the expenses scandal.

Marjory LeBreton made the rounds of the Sunday talk shows to highlight a package of proposed changes to Senate rules on expense claims. However, in an interview with CBC News, she conceded, "The public do not see the Senate as a legitimate institution.

"We have got to fix this, once and for all," said LeBreton. "Otherwise ... the Senate as an institution cannot survive."

LeBreton, who has served the Conservatives in various roles for more than three decades, emphasized that abolition of the Senate was one of the possibilities that the government has asked the Supreme Court of Canada to rule on.

"One of the options that the Supreme Court should have to consider is whether the Senate should be abolished."

Harper, fresh off a tour of South America, is expected to face questions in the House of Commons this week for the first time since the Senate spending scandal heated up, and led to his chief of staff’s resignation.

LeBreton said on the weekend that Canadians have every reason to be angry about the latest expense scandal in the Red Chamber.

"Because it's not seen as a legitimate institution, the public ... obviously react in a very negative way — as you would expect them to do."

As for the government's handling of the expenses affair, LeBreton said she believed that former chief of staff Nigel Wright acted alone in trying to "fix" the matter of Senator Mike Duffy's $90,000 in living expenses.

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Senator Marjory LeBreton says she believes the prime minister's ex-chief of staff acted alone in trying to "fix" the matter of Senator Mike Duffy's $90,000 in living expenses. (Patrick Doyle/Canadian Press)

"It's my personal opinion, but Nigel probably thought he could help fix this."

But LeBreton said she was unaware of any written agreement between Wright and Duffy.

"As far as I know, there's no documents, there's no paper trail. As far as I know, it was an arrangement made between the two of them."

In Cali, Colombia, on Thursday, Harper said that he, too, knew of no paper trail.

Asked if he would disclose the agreement between Wright and Duffy, Harper said, "I'm not aware of any formal agreement on this."

The opposition, however, suspects that the prime minister had a hand in the deal, even if he didn't know the details.

In an interview with CBC News in Toronto, NDP critic Craig Scott said Harper may have set the deal in motion.

"He could well have said something to Mr. Wright like, 'Make this problem go away, the money has to be paid back sometime soon because we're getting killed by this and it'd be better if it were done before the audit was finished' — and then he kinda left it to his chief of staff. It's not impossible that that's the scenario."

LeBreton insisted, however, that the arrangement was not known to the party leadership.

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Senator James Cowan, leader of the Opposition in the Senate, is demanding police involvement in the investigation into the Senator Mike Duffy payment. (Fred Chartrand/Canadian Press)

"You can hardly fault the Conservative Party or the government when it's something we didn't know about," said LeBreton.

The opposition in the Senate, however, expects the RCMP to investigate any possible connection between Wright's bailout of Mike Duffy, with a $90,000 personal cheque, and the editing of the Senate's audit report on Duffy. A Conservative-dominated committee removed damning sections of the draft report.

The Liberal leader in the Senate, James Cowan, said he found it "very suspicious that the prime minister's chief of staff would make a gift of $90,000 to a Conservative senator who's in the midst of a forensic audit."

Cowan added, "We've reached the point where we need trained professional investigators to get to the bottom of this and that's what the police are there for.

"They're looking, I assume, at Mr. Wright's involvement," said Cowan, "and any connection between the payment and what happened in the Senate with the Senate reports ... It's really only going to be the RCMP who can do that detailed, comprehensive investigation."

Cowan was also critical of LeBreton's refusal to sign a letter from both Senate leaders asking the committee chair, Conservative Senator David Tkachuk, to hold public hearings when it reconsiders the matter.

"I asked Senator LeBreton to join me in asking the committee to hold their hearings in public," said Cowan. "She said no."

LeBreton said she would support whatever the committee decides. However, the Conservative majority would effectively decide whether to open the doors. Its previous deliberations, in which the editing of the Duffy report was done, were closed to the public.