Queensland Premier Campbell Newman has asked State Parliament to postpone its endorsement of former LNP treasurer Barry O'Sullivan as a federal senator.

Mr Newman has told Parliament Mr O'Sullivan is under investigation by the state's Crime and Misconduct Commission (CMC).

MPs were set to vote this afternoon on Mr O'Sullivan's appointment to replace federal Coalition frontbencher Barnaby Joyce, who resigned his position in the Senate to move to the Lower House.

But an urgent LNP party room meeting was held this afternoon and Mr Newman has told the Parliament the vote will now be held next month.

"The LNP and Mr O'Sullivan are aware that Mr O'Sullivan is presently involved in a Crime and Misconduct Commission investigation," he said.

"To uphold the integrity of the Senate and to ensure this chamber makes an informed decision, the LNP and Mr O'Sullivan have asked the Parliament to move to adjourn the matter until the CMC has completed its investigation."

The CMC investigation relates to allegations that Moggill MP Bruce Flegg was offered inducements to vacate his seat for Mr Newman.