Labor asked to find budget billions

Labor faces pressure to explain how it would fill an estimated multi-billion dollar savings black hole left by the party's opposition of key government budget measures.

Labor plans to block a raft of coalition policies including the fuel excise and Medicare co-payments, which the government estimates will cost taxpayers $39.345 billion through until 2017/18.

Faced with a count of upper house crossbench supporters, some of Tony Abbott's plans look set to fail but the prime minister maintains "people can change their mind".

"The point I will be making to everyone is what is their plan to tackle Labor's debt and deficit disaster?" Mr Abbott told Sky News.

"In the absence in any suggestions from anyone else, it's the only plan," he said of the government's budget.