The Senate is taking steps to suspend three of its own without pay as the institution looks to distance itself from an ongoing controversy over some members' expense claims.

Claude Carignan, the new government leader in the Senate, announced on Thursday that he will move three separate motions to suspend Mike Duffy, Pamela Wallin and Patrick Brazeau from the Red Chamber for "gross negligence" in managing parliamentary resources.

All three senators are former Conservatives who were appointed by Prime Minister Stephen Harper, and all are under investigation by the RCMP after external auditors found problems with their expense claims. A fourth, former Liberal Mac Harb, quit in August. None of the senators under investigation have been charged in connection with their expense claims.

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The scandal has been deeply damaging for the Conservative government, which came into power with a promise to reform the Senate. Earlier this year, the government announced the leader in the Senate would no longer have a seat at the cabinet table, a move widely perceived to be part of an attempt to contain the controversy within the Red Chamber.

A debate on Mr. Carignan's motions could begin as early as Tuesday and is expected to generate opposition from some senators who believe suspension would be too severe.

If the motions pass, the suspensions would remain in effect until the end of the current legislative session – which may not be until 2015 – or until the Senate votes to reverse the decision. The senators would be barred from collecting their salaries, living and travel allowances, and from using Senate resources.

None of the three senators were in the chamber on Thursday as the notices of motion were read out.

Earlier this year, Mr. Brazeau was barred from the Senate after he was charged with assault and sexual assault. He has pleaded not guilty and is awaiting trial.

Mr. Carignan gave a formal notice of the motions within hours of a note from Mr. Duffy's office stating that the senator will take a medical leave because of unstable angina. In a letter to the Speaker of the Senate sent Thursday afternoon, Mr. Duffy said he was recently told the disease had progressed and was following his doctor's advice to stay off work to "avoid further stress on my system."

Mr. Carignan said senators would have the opportunity to speak in their own defence when the motion is brought forward and added that senators on medical leave can still be suspended.

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He added that suspensions are needed to protect the integrity of the Senate and that the decision was "not at all" about evading a scandal.

Mr. Duffy received about $90,000 from Mr. Harper's former chief of staff, Nigel Wright, to repay expense claims that were called into question. Mr. Wright resigned shortly after news of the payment became public.

Liberal Senator James Cowan said it is within the Senate's power to suspend members, adding that the Senate should not be expected to meet the same burden of proof as police in deciding whether to sanction its members.

He said he supports the idea of disciplining the senators but would speak with with his caucus on Tuesday morning before taking a position on the suspensions.

The Auditor-General is looking into all senators' expense claims in an investigation that is expected to take up to 18 months. Mr. Cowan said it will be important to distinguish between "simple mistakes" that the auditor may turn up and the "pattern of abuse" demonstrated by Ms. Wallin, Mr. Duffy and Mr. Brazeau.

Mr. Duffy is under investigation by the RCMP in relation to allegations of fraud and breach of trust. His expense problems relate to housing claims he made for a secondary residence in the Ottawa area, despite evidence that he spent more of his time in Ottawa than at his Prince Edward Island residence.