Prime Minister Julia Gillard says she does not expect to make more changes to her frontbench team before the next election.

The Prime Minister's new ministry will be sworn in on Monday after outgoing Attorney-General Nicola Roxon and Senate Leader Chris Evans announced they would be quitting politics.

Their decision to step down forced a Cabinet reshuffle just three days after Ms Gillard called the federal election for September 14.

Ms Gillard said that barring any unforseen circumstances the new team is the one that will be in place at the election.

The key changes to Ms Gillard's ministry will see Mark Dreyfus take Ms Roxon's roll as attorney-general.

Immigration Minister Chris Bowen, who wanted to move out of his portfolio, will take over from Mr Evans as the Minister for Tertiary Education, Skills, Science and Research.

Brendan O'Connor will take over Mr Bowen's Immigration portfolio, while Mark Butler will add Housing and Homelessness to his existing portfolio of Mental Health and Ageing.

Parliamentary Secretary Mike Kelly will enter the ministry and will be responsible for Defence Materiel.

The Labor Caucus is expected to elect Stephen Conroy as Senate leader on Monday and Penny Wong as his deputy.

'Appropriate time'

The Prime Minister said that both Ms Roxon and Mr Evans had flagged a year ago that they intended to quit the frontbench.

Despite having only announced the election on Wednesday, Ms Gillard said now was the right time for the pair to announce their intentions.

"I have always had it in my mind that this was the appropriate time to announce new arrangements," Ms Gillard said yesterday.

But some Labor MPs say they were stunned by the timing of the reshuffle.

Opposition frontbencher Christopher Pyne said the Prime Minister's "alibi" about today's resignations does not stack-up.

"She says she's been talking to Nicola Roxon for 12 months about resigning from the Cabinet, and yet 12 months ago she was defeating Kevin Rudd in the leadership ballot and then appointed Nicola Roxon as Attorney-General," he said yesterday.

Mr Pyne has also suggested, based on information from press gallery journalists, that more resignations are likely from the Labor frontbench and from Parliament.

Asked by reporters if she expected further resignations, Ms Gillard replied: "Colleagues come to me from time to time as Nicola and Chris Evans did.

"I don't have before me at the moment anybody who is saying that they want to leave at the next election other than people who have already publicly indicated that that's the case.

"I believe this is the team for the next election.

"Look, we live in a real world and you can never wholly discount that someone has a family circumstance, has an illness present."

Vacancies

Ms Roxon's departure leaves a key vacancy in the seat of Gellibrand, Labor's second safest seat with a margin of 24 per cent.

Meanwhile, former NSW premier Morris Iemma is considering running for the seat of Barton, where another former attorney-general, Robert McClelland, is retiring at the election.

Ms Gillard says the departure of Ms Roxon and Mr Evans gives her the opportunity to promote "fresh talent with fresh ideas".

Three MPs have been promoted into Parliamentary Secretary roles during the reshuffle.

Yvette D'ath will be responsible for Climate Change and Energy Efficiency, Kelvin Thomson will take on Trade, while Melissa Parke will work on Mental Health, Homelessness and Social Housing issues.

Key movements