Scott Morrison is facing pressure to attend a major global climate change conference where Australia is expected to increase its emissions reduction goals.
The coalition government has been tiptoeing towards adopting a 2050 net zero greenhouse gas target ahead of November's COP26 talks in Glasgow.
Labor leader Anthony Albanese said the prime minister should commit to travelling to the United Nations climate change conference.
"He should represent Australia. If he doesn't, it's because he's embarrassed about Australia's position," Mr Albanese told reporters on the NSW Central Coast.
Foreign Minister Marise Payne said attending the conference was a significant undertaking but insisted Australia would have a senior representative at the talks.
"It involves the two-week domestic quarantine as well. So no final decisions have been made," she told ABC radio.
While the government is planning on releasing a long-term emissions reduction plan before COP26, the Nationals have so far stood in the way of the 2050 commitment.
Mr Morrison said he had not made a final decision about attending COP26, which is considered the most important global climate conference in years.
"I mean it is another trip overseas and I've been on several this year and spent a lot of time in quarantine," he told the West Australian newspaper
"I have to focus on things here and with COVID. Australia will be opening up around that time, there will be a lot of issues to manage and I have to manage those competing demands."
The prime minister on Sunday started two weeks of quarantine after returning from the US.
He has also travelled to the UK, France, Singapore, New Zealand and Japan during the pandemic.
Deputy Prime Minister Barnaby Joyce said a decision on the target would be up to the Nationals party room.
He said protecting regional jobs would be crucial to signing up, which he argued other countries had done just to get people "out of their hair".
"For us, we have to deal with the consequences," Mr Joyce told Seven.
"We've been bitten once before with the Kyoto protocol. We don't intend for it to happen again."
Finance Minister Simon Birmingham said there were environmental and economic grounds to support the target.
"There's many reasons why Australia does need to chart the course to net zero," the senior Liberal cabinet minister told Triple M.
Nationals senator Matt Canavan has declared he is "dead-set against" the target, a position fellow Queenslander George Christensen holds.
Deputy Nationals leader David Littleproud said the party would need to see any detail before it committed to a plan.
"The fact is, regional Australians have paid most of the bill for reducing emissions," he told the Nine Network.
"We've paid that bill. It is time to square the ledger."
Resources Minister Keith Pitt is remaining tight-lipped about the prospect of the junior coalition partner supporting a 2050 goal until a proposal comes before the party room.
Victorian Nationals MP Darren Chester, who it taking a break from the party, said Australia needed a plan to reduce emissions.
