Minister's exit could prompt Abbott reshuffle

The Independent Commission Against Corruption has claimed another political scalp, this time a federal minister. 

Senator Arthur Sinodinos has resigned as Assistant Treasurer, clearing the way for the Prime Minister to reshuffle his front bench. 

As far as distractions go, a Minister before a corruption hearing is a pretty big one.

Arthur Sinodinos - former chief of staff to John Howard turned Senator - stood aside in March, and after nine months resigned as Assistant Treasurer.

"The prime minister and I thought it was a good idea for me to announce my resignation because these ICAC proceedings are taking longer than I thought," Senator Sinodinos said.

The Independent Commission Against Corruption has questioned the Senator about his former role as director of Australian Water Holdings - which ICAC is investigating. 

In a statement, the Prime Minister said: "Knowing Arthur as I do, I'm confident he'll be vindicated". 

"Nevertheless, the Government does need an Assistant Treasurer for the preparation of the Budget," he said.

The widely respected Senator says he wants the freedom of speech that comes with sitting on the backbench. 

He started with a swipe at colleagues, after his resignation was leaked to the media. 

"I was working on the basis that I would exchange letters with the prime minister today, and he would make an announcement about a replacement probably Sunday and whatever other arrangements he might be wishing to contemplate," Senator Sinodinos told Sky News.

The Prime Minister has said he'll announce a replacement Assistant Treasurer in the next few days and there's speculation he's preparing to reshuffle the front bench.