Opposition Leader Tony Abbott has come out swinging at newly sworn-in Prime Minister Julia Gillard, saying Labor has changed the salesman but not the product.
Abbott congratulated Gillard, but said it was his job to ensure she is never elected leader of the Australian people.
He also thanked former PM Kevin Rudd for his service, saying that service in high office is a privilege and a burden, especially on families.
"Prime Ministers should not be treated this way," said Abbott, who himself came to power in a Liberal party leadership spill last year.
He called the ousting of Rudd an "ugly assassination".
The dynamic between Abbott and Gillard has been a subject of conjecture in the past, as the two often displayed a friendly camaraderie during parliamentary meets.
"We agree on many things," said Abbott, saying that both he and the new PM believe in rewarding hard work and supporting families and businesses.
"But the difference is how we think those noble objectives are realised," he added.
Abbott said Gillard was likely to pursue Labor policies, which he roundly attacked, albeit without offering alternatives. He branded Gillard the 'co-author' of all the major initiatives opposed by the coalition.
"They were both in denial over pink batts, they were both incompetent on border protection," Abbott said.
He also attacked Australia's first woman prime minister for a controversial school building plan, which he called 'school ripoffs'.
On the deeply contentious issue of mining, Abbott pointed the finger at Gillard as the co-author of what he calls the government's "new great big tax" on resources.
Gillard cancelled taxpayer-funded advertisements for Labor's Resource Profits Super Tax in her first speech as leader fo the party, and mining giant BHP Billiton did the same almost immediately afterwards.
However, Abbott predicted she would remain firm on implementing the tax devised by her predecessor.
"Until she pulls the revenue (from the budget), she is just as committed to this tax that would be deadly to the economic future of this country," he said.
In parliament, Abbott congratulated both Gillard and newly-chosen Deputy PM Wayne Swan on their promotions, and offered his condolences to Rudd.
"A midnight knock on the door followed by execution is no way a leader should be treated," he reiterated.
Abbott told Question Time that Rudd's ouster was proof the government had 'lost its way', but conceded that he respected the abilities of the new PM.
His first question to Gillard in parliament was on whether she would withdraw the $12 billion budget revenue anticipated from the RSPT, to which she replied that negotiations would continue, lead by Treasurer Wayne Swan.
While public figures and the media focussed on the fact Gillard is Australia's first female prime minister, Abbott said the day was 'historic' because it was the first time a PM had been replaced due to pressure from internal party factions.
"It is historic because this is first time the style of NSW Labor has come to Canberra," he said, referring to Premier Kristina Keneally's ouster of Nathan Rees late last year.
"It is the first time a prime minister elected by the people has been executed by union and factional warlords," he added.
"This style of NSW mafia has been well in evidence over the last 24 hours."
Abbott said his party offered the Australian people 'a better way'.
