Scott Morrison wants cabinet to approve the target before he jets off to a crucial international climate change conference which starts at the end of the month.

But the Nationals are yet to agree on the government’s energy plan ahead of Tuesday’s joint coalition partyroom meeting.

Morrison has indicated cabinet will make the final call rather than a vote of MPs because the pledge will not be legislated.

Joyce said the prime minister was correct to imply the Nationals agreement would not necessarily be needed.

“But we want to make sure we maintain a tight coalition,” he told the Nine Network on Tuesday.

“The nation expects that of us and we will make sure we give our best endeavours to do that.”

The deputy prime minister said a cabinet split between the coalition parties would be very difficult.

“If a decision is arrived at that is agreed to, it’ll be by reason that the National Party agreed to it in cabinet,” he told Sky News.

“If the National Party didn’t agree to it in cabinet then that in itself is a item of conjecture that doesn’t sit well.”

Resources Minister Keith Pitt – a Nationals MP not in cabinet – defended how long it was taking for his colleagues to reach a decision on a 2050 net zero target.

“The climate is changing, it’s always changed,” he told ABC radio.

“Do I think that Australia can change the temperature of the globe if we shut our economy? I don’t think it will make one iota of difference.”

Pitt said he would back the government’s decision as a member of the ministry but insisted it was still not settled because the Nationals were deliberating.

“Right now, it’s a no, as the deputy prime minister has said, but those discussions are ongoing,” he said.

The government has ruled out lifting its 2030 emissions target from a 26 to 28 per cent reduction on 2005 levels.

But updated projections for that date are expected to be released this week.

Morrison says the path to net zero by 2050 will not be linear.

Moderate Liberal MP Dave Sharma said it was in Australia’s security and economic interests to back a net zero target.

“Nations will expect us to have a policy when we turn up to Glasgow and that’s when it will be announced,” he told the ABC.

Opposition Leader Anthony Albanese argues a 2050 net zero target will not be taken seriously unless it is legislated.

“We have a government and a nation being hostage to a few people in the National Party,” he said.