Former Defence Minister Willie O'Dea has branded Ivor Callely an "embarrassment" and questioned why current legislation means the senator cannot be sacked.
O'Dea, who resigned last February over comments he made about a Sinn Fein election candidate, said the last thing any Fianna Fail TD wants to see is "a headline with the word Callely in it".
"He's a constant source of embarrassment," he added.
His comments came as Senator's investigating mobile phone expense claims by Callely are expected to be asked today to adjourn their inquiry for two weeks to give the politician more time to seek legal advice.
The Select Committee on Members' Interests has received submissions from four senators in relation to complaints over expenses.
Callely, who lost his party whip and is currently on suspension pending the outcome of the committee's investigations, has told the Seanad watchdog he needs two weeks to discuss allegations he used fake receipts to claim up to €3,000 in phone expenses with his barrister, who is currently on holiday.
Callely first came under the spotlight recently over travel expenses of €80,000 he was claiming from his holiday home in Cork, and then again when it emerged he had made expenses claims of nearly €3,000 for mobile phones using receipts from a company that had ceased trading.
It emerged at the weekend that there are queries over mileage claims he was making while junior health minister.
"For the committee not to grant it [the two-week adjournment] would give him strong grounds for a judicial review on the basis that he's not being given his basic rights to defend himself," said a political source.
The select committee will also discuss a response from fellow-Fianna Fail senator Ann Ormonde over travel expenses claimed for a period from her holiday home in Waterford, as well as a reply from a third Fianna Fail senator, Larry Butler, over travel expenses he claimed from his Kilkenny residence when his Dublin home was listed as his address.
In relation to a separate complaint against Independent senator Ronan Mullen over not revealing the name of a politician who advised him to falsify his expenses, the committee is expected to decide this is a non-issue.
It is unclear if the Seanad watchdog will investigate reports that Ivor Callely claimed expenses for up to 5,000 miles a month while junior health minister and living three miles from his office.
Fine Gael Justice spokesman Senator Eugene Regan yesterday reiterated his call for Taoiseach Brian Cowen to seek Mr Callely's resignation following media reports that he received €87,000 in mileage expenses over two years while living centrally in Clontarf.
O'Dea also said Callely may not be allowed back into his post until he has repaid the disputed expense claims.
But it emerged that Callely could continue to collect his €65,000 salary in his absence.
"Maybe there should be a system where somebody could be impeached if they break the rules," said Deputy O'Dea.