The vote on whether Mike Duffy, Pamela Wallin and Patrick Brazeau will be suspended without pay but be allowed to retain health and dental benefits, as well as life insurance, is expected to be held Tuesday.
Some Conservative senators have raised concerns that the motion would mete out the same penalty for each senator, even though the details of their cases are different.
Bob Runciman, a former solicitor general of Ontario, said he's been assured he can vote on each case separately.
Runciman made it clear he is loath to vote against a government motion, but is satisfied he will be able to abstain in the case of one of the senators. He won't say who that senator is.
A Senate source told CBC News several Conservative senators expressed anger at a Conservative Senate caucus meeting last week about how unfair they felt it was not to be able to distinguish how they voted about each senator.
The amount of money each owed in disallowed expenses varied. Wallin repaid the most money, at $140,000, Duffy's $90,000 tab was paid on his behalf by the prime minister's former chief of staff, Nigel Wright, and Brazeau, whose wages have been garnisheed, is still repaying the $50,000 assessed to him
A senior Conservative Senate source confirmed to CBC News that the plan is to allow the Senate a separate vote on Duffy, Wallin and Brazeau. The motion to suspend them is divided into sections A, B and C, with the senators's names attached to each section.
However, some Liberal Senate sources wonder how the Conservative Senate leadership will divide one motion into three votes, especially since a closure motion is being imposed to limit debate time on the one motion.
Liberal sources point out dividing one motion into three votes has never been done before and is without precedent in Senate history.
Some senators have been trying to find out if the three senators facing suspension will be allowed to stay in the Senate pension plan, if they are allowed to keep their benefits.
Duffy, Wallin and Brazeau, all Conservatives, took their Senate seats in January 2009 and each has two years to go before becoming eligible for a Senate pension once they reach age 55, although only Brazeau is under 55.
Their suspensions, if the vote passes, will last until the end of the Senate session, two years from now when the next federal election is expected.
Senate administration was unable to provide details to CBC News last week about whether the suspension time will count as pensionable time if the three are suspended without pay this week.
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