Brett Mason told colleagues he was planning to challenge George Brandis for the No. 1 spot on the LNP's Senate ticket in the weeks leading up to his demotion from the frontbench, sparking speculation he may be offered an overseas posting to protect the Attorney-General's position.

Senator Mason was, until Sunday, the Parliamentary Secretary to Foreign Minister Julie Bishop. When contacted about his plans to challenge his fellow Queenslander he refused to confirm or deny the reports.

A photographer adjusts the placement of the new ministerial appointments in a photograph with Prime Minister Tony Abbott and Governor-General Sir Peter Cosgrove at Government House in Canberra on Tuesday. Credit:Andrew Meares

But sources have told Fairfax Media Senator Mason has privately confided his plans to try and oust Senator Brandis from No. 1 in a move they believe would have been successful and in the process humiliated one of the Prime Minister's office's closest confidantes.

One Liberal said it was likely that Senator Mason and possibly his other dumped colleague, West Australian Senator David Johnston, would be offered overseas postings.