Prime Minister Tony Abbott is expected to reshuffle his ministry after Arthur Sinodinos resigned as assistant treasurer.

The new lineup could be announced as early as this weekend but some sources suggest Mr Abbott will wait until late January just before parliament resumes for 2015.

"I will be resigning as assistant treasurer with effect from close of business today," Senator Sinodinos said in a statement on Friday.

The ex-Howard government adviser had stood aside from the ministry role to give evidence in NSW Independent Commission Against Corruption inquiries.

However, the inquiry reports have been delayed until March 2015 or beyond and the government needs an assistant treasurer to work on the May budget.

Senator Sinodinos said the prime minister had advised him he could not resume his duties until the ICAC matters were completed and reported on.

"I am confident that when the reports are finally released, I will not be subject to any finding of corrupt conduct or illegality," the former NSW Liberal Party treasurer said.

Senator Sinodinos, who will remain in the upper house as a backbencher, said he had been discussing his future with Mr Abbott and Liberals federal director Brian Loughnane in "recent weeks".

A poor showing in the polls and recent ministerial blunders have put pressure on the prime minister to make some changes to his ministry team.

Deputy Liberal leader Julie Bishop told reporters in Brisbane on Friday any changes were a matter for the PM.

"I think we have a very strongly performing team," she said.

Education Minister Christopher Pyne said he was sorry Senator Sinodinos had felt the need to resign but understood why.

"He is a fine man and committed to serving others," Mr Pyne wrote on Twitter.

Employment Minister Eric Abetz said Mr Abbott "doesn't need my gratuitous advice" about when to do a reshuffle.

Labor MP Andrew Leigh said a series of gaffes by Treasurer Joe Hockey's showed the need to fill the assistant treasurer role immediately.

"You don't envy the prime minister because there are plenty more ministers that have been more naughty than nice," Mr Leigh said.

"This government is in more trouble than a Santa Claus impersonator stuck down a chimney. It's got all kinds of strife going on."

Defence Minister David Johnston has been tipped as a potential cabinet casualty.

© AAP 2014