4BC News: Treasurer Wayne Swan has challenged the opposition to reveal how much its election promises are going to cost once the federal budget numbers are released in May.
Mr Swan says the government will account for its big spending on education and the national disability insurance scheme through savings in the budget on May 14.
With the federal election date set for September 14, the opposition has no excuse not to reveal its costed policies after the budget is brought down, the treasurer told ABC TV.
"Failure to do so will very clearly indicate what their agenda is, which is not to put out detailed policies based on forecasts based on either information from the budget or the Parliamentary Budget Office," he said.
The opposition's strategy was to release as little of their costings as possible, he said.
"They're out there saying that they will have lower deficits, lower taxes and of course more spending," Mr Swan said.
"That is just a magic pudding."
Shadow treasurer Joe Hockey has said the May budget numbers will be questionable and the coalition would rely only on figures from the pre-election fiscal outlook (PEFO).
The departments of Treasury and Finance will release the PEFO 10 days after the writs for the election have been issued on August 12.
Mr Hockey said on Wednesday the coalition had submitted more than 50 initiatives to the Parliamentary Budget Office for costing, but it was struggling to get through them.