Clive Palmer has accused Prime Minister Tony Abbott of "deserting" Australians by travelling overseas and leaving Treasurer Joe Hockey to sort out the budget deadlock at home.
But the Palmer United Party leader said the trip was unwarranted and Mr Abbott should not "desert the people of this country".
Mr Palmer had dinner with Mr Hockey on Tuesday night as part of ongoing budget negotiations between the government and PUP representatives.
On Wednesday, Mr Palmer said he felt sorry for the Treasurer, echoing the comments of PUP Senator Jacquie Lambie.
"I do sympathise with the Treasurer because the Prime Minister's left the country at a time of critical economic crisis which I don't think is a good thing," he told ABC radio.
"I think the Treasurer did show some leadership in the fact that he's trying to sort out this mess that he's been left with by the government and I think that's very commendable."
Mr Palmer is scheduled to have lunch on Wednesday with Education Minister Christopher Pyne, while Mr Hockey will fly from Brisbane to Perth to meet PUP senator Dio Wang. It is the final in a series of meetings with Senate crossbenchers for which the Treasurer has criss-crossed the country.
Senator Lambie on Tuesday also said that she felt sorry for Mr Hockey, accusing his colleagues of abandoning the Treasurer as he attempted to sell his unpopular budget.
But the Palmer United Party senator has warned that sympathy will not lead to her changing her mind on a raft of budget cuts proposed by the Coalition government.
Senator Lambie said the budget ''was really tough and the rest of the Liberal Party has started to move away from him. It wasn't just Joe's budget it was the Liberal Party's budget.''
''I'm really disappointed - they call themselves this team and they've left Joe out there to hang - I find that quite disgusting. I can see why Joe is getting pissed, I don't blame him. It wasn't just Joe – while he's out there trying to sell the budget, the rest are doing a runner on him.''
Mr Palmer said that while the two agreed on the need to align revenue with expenditure he made his thoughts about the fairness of the budget known.
''I don't think the budget is fair at all,'' he said.
Mr Hockey on Wednesday denied that his budget disproportionately hit the poor and said ''everyone is being slugged'', adding that his complaints about the difficulty in selling the job were an attempt at humour.
''People are missing some self-deprecating humour along the way; it was always going to be a challenge,'' he told ABC Radio.
But in a sign of hope for Mr Hockey, Mr Palmer has toned back his strident criticism of the government's budget and has not ruled out supporting a watered-down version of the proposed GP-fee.
''We need to actually see the hard policy,'' he said, adding that as a wealthy person he had no problem with paying the $7 fee but did not want to see it imposed on pensioners and the poor.
Mr Hockey said on Wednesday that the government was ''prepared to discuss these things'' one day after the Health Minister Peter Dutton said he was looking ''seriously'' at a plan to exempt disadvantaged people from paying the fee, including pensioners.
Shadow Treasurer Chris Bowen called on the government to be ''upfront'' about what it plans to put forward so that the parliament can deal with it.
But he said there was no form of GP co-payment Labor would accept, consigning the measure's fate to the crossbenchers.
Education Minister Mr Pyne might face a tough challenge convincing Mr Palmer about the merits of university deregulation.
Mr Palmer said on Wednesday ahead of his lunch with Mr Pyne that his party stood behind university students, not the government, and remained opposed to changes that peg HECS loans to the government bond rate.
Mr Palmer said the Education Minister faced a ''pretty hard task'' to convince him on deregulation. ''I would probably enjoy the lunch but it’s a very difficult thing (deregulation) to look at,'' he said.
with James Massola and AAP