New South Wales Premier Morris Iemma has sacked his unpopular Treasurer Michael Costa in the wake of the state's failed electricity privatisation push.

Mr Iemma will reshuffle his Cabinet today after sacking Mr Costa overnight in response to enormous pressure from his backbench, Cabinet and Labor Party members and luminaries.

Labor backbenchers are beginning to speak out about Michael Costa's aggressive style.

On ABC Radio's The World Today (listen at midday on ABC local radio), backbencher Geoff Corrigan is one who says he is not sad to see the now former NSW treasurer go.

"Michael is a crash through or crash type person," Mr Corrigan tells The World Today.

"That's been obvious for the past year in his determination to get through this electricity stuff and all I can say is personally I won't miss that style.

"But I've never been afraid to stand up to him so I've had no problems with it. But some people who cower before his onslaught when they're in discussions realise that at times you can't always give in, you've got to stand up and be counted when you're dealing with people like Michael Costa," Mr Corrigan says.

Mr Costa held a media conference about his future at 10:00am (AEST).

The outcome of the reshuffle will be announced after a Labor Caucus meeting later today.

Former education minister Carmel Tebbutt will be confirmed as the new Deputy Premier after the parliamentary Left faction endorsed her yesterday.

Ms Tebbutt has told the ABC she is excited about her new role.

"I'm honoured to be nominated for the position of deputy premier," she said.

"Of course it has to be determined at the Caucus today, but it's an opportunity for me to serve at a senior level of Government and I'm very excited by the prospect."

She says the reshuffle is a chance to renew the frontbench.

"I'm very, very much looking forward to serving with the Premier as part of a new Cabinet [with] new energy, new enthusiasm, focused on the challenges ahead."

The Left faction also voted to elevate Granville MP David Borger to the ministry.

Nathan Rees, Verity Firth and Kristina Keneally are all expected to receive a promotion into more senior portfolios, and John Della Bosca has been promised a return to the frontbench after being cleared of wrongdoing in the Iguanas nightclub scandal.

Reba Meagher is expected to be a loser in the reshuffle after a series of incidents in her health portfolio.