Josh Frydenberg and Steven Ciobo, who serve as parliamentary secretaries to Prime Minister Tony Abbott and Treasurer Joe Hockey, have emerged as the front runners.

If either of those was promoted, three Liberal MPs - Dan Tehan, Kelly O'Dwyer or Christian Porter - have been tipped to fill the vacancy created.

Senator Sinodinos stepped back from his portfolio almost two weeks ago over his links to Australian Water Holdings, a company linked to former Labor power broker Eddie Obeid.

He has consistently denied any wrongdoing over allegations that he stood to make up to $20 million as a director at the company and says he will be vindicated at the ICAC hearing, where he is scheduled to appear on Wednesday.

Liberal MPs told Fairfax Media on Monday that there was a developing view in the party room that Senator Sinodinos would be sidelined for longer than expected by the wide-ranging ICAC inquiry and that it could be difficult for him to return once the hearing ended.

Of the contenders, Mr Frydenberg played a key role behind the scenes in the repeal day last week.

Mr Ciobo, on the other hand, already reports directly to the Treasurer and is seen as part of the ''Hockey Club'', a group of economically dry MPs led by Mr Hockey, which also includes rising stars such as Finance Minister Mathias Cormann and junior Infrastructure Minister Jamie Briggs.

Several Coalition MPs confirmed to Fairfax Media that Mr Ciobo would be Mr Hockey's choice.

One said that no one had yet written off Senator Sinodinos' chances of returning but admitted there was ''a lot of chatter'' about the vacancy and that ''Arthur could be gone for a while''.