Senator Ivor Callely is expected to look for an extra fortnight to put together his case for the probe into his expenses claims.
The Fianna Fail senator is understood to be seeking an adjournment of the investigation because his lawyers are on holiday.
The Seanad Committee on Members' Interests will meet privately on Monday and is expected to agree to the request.
The aim of Monday's meeting was to decide if the committee had sufficient information to proceed with its inquiries at this point.
It is now likely to agreed to a postponement to allow time for additional information to be submitted.
Mr Callely's legal adviser is believed to be on holidays at the moment and the committee is expected to grant a request for a delay because the senator is entitled to time to prepare his case.
The adjournment is likely to be for two to three weeks, after which time a public hearing into the allegations is expected.
The committee had originally given Mr Callely until Monday to submit "a detailed statement" on allegations that he used forged receipts from a phone equipment company, that had gone out of business, to claim almost €3,000 expenses.
A similar Oireachtas probe last month resulted in Mr Callely being suspended for 20 days for misrepresenting his normal place of residence to claim travel expenses from his holiday home in Cork instead of his Dublin address.
The latest investigation comes after revelations that Mr Callely submitted an expenses claim to the Oireachtas Commission for almost €2,900 for four different mobile phones and car kits in November 2007.
The senator said he bought the products between 2002 and 2006. The invoices came from a company called Business Communications Ltd that was wound up eight years earlier.
Mr Callely issued a statement later saying he had paid back the money, that he had acted in good faith and made a genuine mistake.
Mr Callely is one of four senators who had complaints made against them to the committee.
Fianna Fail senators Anne Ormonde and Larry Butler are also being asked to deal with complaints concerning travel expenses from Waterford and Carlow respectively.
Independent Senator Ronan Mullen has to respond to a complaint that he revealed in a radio interview that a senator colleague had advised him to use his old home address in Galway to claim mileage instead of his current Dublin residence.
He has objected to being included with the other three senators as there is no complaint against him regarding his expenses.