Prime Minister Tony Abbott says he won’t surrender his budget in the face of pressure to compromise over its most unpopular measures.

Mr Abbott is confident the coalition’s first budget will pass the Senate because the alternative would be a double dissolution election.

Senior government ministers have signalled compromising on key budget reforms such as higher education interest rates and the GP co-payment, amidst a fierce public backlash and a hostile Senate.

Continuing the budget sell on Saturday, Mr Abbott said his team “absolutely” understood the “iron necessity” of sticking with difficult and unpopular budget measures.

“We are not going to surrender our budget commitments,” Mr Abbott told reporters in Adelaide.

But negotiations were inevitable.

“You have got to negotiate your legislation through the parliament,” he said.

Mr Abbott was confident that the government would get the budget through the Senate in the end, because the alternative would be a double dissolution election.

“Because let’s face it, there have been many governments over many years that have had to negotiate budgets through the Senate.

“The only time that wasn’t successfully done … that was a different bill in 1975.”

Last week, Mr Abbott appeared to back away from a threat to hold a double dissolution election after earlier signalling incoming Senate cross-benchers would be unlikely to keep their seats if there was a new election.

Labor, the Greens and Palmer United Party have vowed to block changes such as the Medicare co-payment and pension cuts.