Labor has announced plans to punch an $11.4 billion hole in the federal budget by joining with the Greens in the Senate to block a raft of measures the government says are crucial to its fiscal repair task.

The move comes as the generally anti-fossil fuel oriented Greens party declared it would join Labor in opposing the restoration of the federal fuel excise because the government has pledged to spend the extra $2.3 billion it would raise exclusively on roads.

The crucial revenue measure now appears doomed because it is unlikely to be supported in the new Senate after June with the Palmer United Party and the Australian Motoring Enthusiast Party also opposed.

Labor leader Bill Shorten unveiled the opposition's attitude to 32 provisions of the budget on Tuesday – 20 of which the ALP will oppose. These include the scrapping of the $800 Seniors Supplement for self-funded retirees, which was meant to recover $1059 million over five years from July. Concession card holders will continue to receive the payments beyond June.

Labor will also oppose a government plan to freeze the rates of Family Tax Benefit payments for two years at a saving of more than $2.5 billion over four years. Another change to limit the eligibility to FTB (B) payments to those with with children under six is also to be blocked, denying the Abbott budget repair task another $1.9 billion.

Mr Shorten said Labor had decided to support about $2.8 billion worth of savings including the calculation of superannuation income in eligibility for the Commonwealth Seniors Health Card and the lowering of the income cut-off for Family Tax Benefits (B) from $150,000 a year to $100,000. That will see $1.2 billion less spent on that assistance.

Opposed, however, are the plans to introduce a $7 GP co-payment, the delayed pension eligibility age to 70 by 2035, and new work-for-the-dole requirements on young people slated to save $1.2 billion.

Signalling the fight, Mr Shorten said:

"I will not stand by and let this government make it harder for parents to take sick children to the doctor.

"We will not stand by and watch pensioners be slugged and families be slugged up to $6000 a year."

The government's hopes for much of its budget now turn on the clutch of crossbench senators due to take their seats in the upper house from July.

Central to that is the Palmer United Party, which will control up to four crucial Senate votes needed. The party's head, lower house MP Clive Palmer, is set to announce his position on disputed budget measures on Wednesday.

The government remains privately hopeful that much of the political posturing by opposition and cross-bench figures will eventually give way to a degree of legislative compromise.

Mr Shorten's decision to block so much of the budget has left the ALP open to the charge that Labor is overly negative and has no plan to restore the budget to surplus.

Asked if he would commit to rolling back any savings the government was successful in implementing, Mr Shorten was less definitive.

"I commit to doing my very best to stopping these changes happening. Tony Abbott has a fight on his hands. We didn't ask him to do these crazy ideas, these unfair ideas," he said.

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