Speculation has risen in the past week in the wake of poor Coalition opinion polls that Mr Costello might re-nominate for the seat of Higgins, raising hopes among his supporters that he might run for the Liberal Party leadership at some stage.

The latest Newspoll showed the Coalition slumping to a 41 per cent two-party preferred support level versus Labor's 59 per cent, and a dip in Opposition Leader Malcolm Turnbull's personal ratings.

''If he is going to stay in the Parliament, a man of his talent really does need to be in the front row, not sitting on the sidelines,'' Mr Abbott said yesterday.

''In this business you're either in the main game or you're not.''

Mr Abbott played down the prospects of Mr Costello ever becoming leader, saying that his time had come and gone.

''Peter is going to be one of the greatest prime ministers we never had,'' Mr Abbott said.

''[His] tragedy is that his time never came, and that's one of the things that happens in politics.''

After the election in November last year Mr Costello said he would seek a future in the private sector, but the former treasurer has recently taken up a columnist position with Fairfax newspapers, along with an appointment to a World Bank anti-corruption panel.

Opposition environment spokesman Greg Hunt said he was satisfied with Malcolm Turnbull's leadership. David Alexander