It will allow the Coalition to avoid sustained financial scrutiny and circumvent an expected massive ALP and union-funded advertising blitz over the opposition's final costings. The Coalition declared Labor was ''in tatters'' after the heads of the Treasury and Finance departments rebuffed its ''black hole'' claim. Campaigning in Perth on Friday, Mr Rudd continued to cite $70 billion as the amount the Coalition planned to cut, and said he stood by his ''$10 billion'' claim of the previous day. At a news conference where a Labor staffer accidentally switched off the lights, the air conditioning did not work and at least one person fainted, Mr Rudd appeared irritable. Other senior government figures also stood by the claim, despite the Treasury statement.

Pressed on the origins of the $10 billion figure, Deputy Prime Minister Anthony Albanese confirmed it came ''from Treasury and Finance''. However, he later acknowledged a central Coalition point, also made by Treasury, that ''if you change the assumptions, depending on the detail of the opposition policy, then you might get a different outcome''. In a sign of his growing confidence, Mr Abbott has dropped plans to tour Western Australia next week in favour of spending more time in western Sydney. Liberal insiders say Mr Rudd's slide and Friday's ICAC findings have helped bring previously unreachable Labor seats within grasp. These include the two Labor jewels of McMahon, held by Treasurer Chris Bowen with a margin of 7.8 per cent, and Watson, held by Immigration Minister Tony Burke on 9.1 per cent. Mr Abbott is also expected to withhold Parliamentary Budget Office costing detail when he releases his final bottom line figure, meaning voters will only get the full picture 30 days after the election when the PBO publishes its comprehensive report.

Asked precisely when his side would give voters the final budget impact, Mr Abbott said: ''It will be when we're finished releasing policies and I suspect that will be towards the end of the week.'' On Thursday, Treasury Secretary Martin Parkinson and Finance Department Secretary David Tune issued a public statement advising that neither had examined the opposition's policies, and any modelling used for costing government policies could not credibly be applied to the federal opposition. On Friday morning, Christopher Pyne said the departmental secretaries had ''torpedoed'' Labor's campaign. ''Kevin Rudd had built his campaign around attacking the Coalition on a negative way and what [the] Parliamentary Budget Office, Finance and Treasury did yesterday was call Kevin Rudd out to be a make-up artist and to have been lying about the Coalition's costings,'' Mr Pyne said. Loading

''Anthony Albanese can say whatever he likes; yesterday Kevin Rudd confidently went out and accused the Coalition of having a $10 billion black hole; in the afternoon the objective heads of the department said that was utterly false. ''Kevin Rudd's campaign is in tatters today.''