Treasurer Joe Hockey has rejected advice from his mentor, Peter Costello, to drop the proposed $7 fee to visit a doctor.
And Mr Hockey has said there is still hope for some measures in the budget to get through, citing the inconsistency of the government's opponents in the Senate and warning commentators against "counting their chickens" in declaring individual items dead.
Mr Costello, a former Liberal treasurer, urged the government to "reboot" its budget sell and ditch unpopular measures that are unlikely to pass the Senate, including the $7 GP fee.
But Mr Hockey has rebuffed the advice, saying the fee was crucial to making Medicare sustainable.
"It's not good advice because, frankly, our budget is part of an overarching economic action strategy," he said.
"We are dealing with issues one at a time."
Labor has seized on Mr Hockey's refusal to budge saying it shows the Treasurer doesn't listen to anyone ''but himself''.
''Health experts and professionals, and now even your own side agree the GP Tax is a disaster Mr Hockey,'' Labor's Health spokeswoman Catherine King said in a statement.
''It's time to start listening and axe the GP Tax.''
Mr Hockey stressed that there was still plenty of time to negotiate on key measures before they were due to begin next year or later.
''I think it is important that we carefully and methodically go through a process of engagement, which is exactly what we are doing,'' he said.
''It is not unusual to have various initiatives held up in discussion in the Senate.''
The Treasurer has hit the road in the past fortnight, visiting crossbench senators in their home cities to negotiate on the remaining individual measures still to pass the Senate.
Mr Hockey said the crossbenchers had given him various pieces of information to analyse and he in return had invited them to meet Treasury officials for a more detailed explanation of the budget.
And he hit out at "inconsistency" of some of those he is dealing with and singled out Labor for attacking the deficit levy and then voting for it.
"So I am very sceptical about public pronouncements by individuals versus how they actually vote in the Parliament," he said.
"We're dealing with people who are entirely inconsistent; there is a level of inconsistency from our political opponents that we have to deal with," he told ABC Radio.
But Mr Hockey seems to still have some way to go to persuade crossbenchers of the merits of his budget, with Democratic Labour Party senator John Madigan predicting at the weekend that the measures would produce an increase in domestic violence, drug and alcohol abuse and mental health issues.
Interviewed on ABC TV's Insiders on Sunday, Senator Madigan said he believed the budget was unfair because it hit the poorest hardest.
''If we attack those people with the least, I believe we're going to have more domestic violence, drug and alcohol abuse, vandalism, mental health problems - and what's the cost going to be to mop that up?'' Senator Madigan said.
And the Palmer United Party has also refused to support deregulation of university fees when the Abbott government presents legislation to the Senate. PUP leader Clive Palmer's stance was backed by one of his senators, Jacqui Lambie, who called on the Nationals to ''grow a set'' and oppose fee deregulation.
Labor leader Bill Shorten appeared at a Melbourne University rally on Monday, where he signed a pledge that Labor would block university funding cuts, fee deregulation and increased interest on student debts.
Mr Shorten said Education Minister Christopher Pyne was "arguably the worst education minister this country has ever seen".