The unmet demands that ultimately broke up the Coalition

Nationals Leader David Littleproud announced on Tuesday that his party would not sign a post-election federal Coalition agreement with the Liberal Party - only the fourth time this has happened in a century and the first since the 1980s - after negotiations failed.

"This is a principled decision," Mr Littleproud told reporters in Canberra.

"We come here, not wanting to have to scrap over every last crumb, but to make sure that we get what we deserve."

Ms Ley, who has promised a wide-ranging review of all policies taken to the election, said at a press conference that she had asked Mr Littleproud to respect her party's processes.

Mr Littleproud blamed the Liberal Party leader's refusal to commit to retaining four key policies: nuclear energy, divestiture laws to break up the big supermarkets, better telecommunications services for the regions and the $20 billion Regional Australia Future Fund.

"These were positions that we made very clear to Sussan," Mr Littleproud said.

"I'm not going to divulge our conversations, but I think she is to the juncture where she would like to get her party to that point ... She should be able to do that as well."

Ms Ley said she could not agree to the Nationals' demands as the Liberal Party would not commit to policies before completing a review of its failed election campaign.

She ruled out appointing a temporary shadow ministry, despite indicating hopes to re-establish the Coalition.

"The shadow ministry that I appoint, of worthy and talented Liberals, are well equipped to take the fight to the next election, and they will," she said.

"Any discussions with the Nationals - may happen on the eve of the next election - and may revolve around what is implemented post the next election, when a Coalition forms in government."

Ms Ley said the Nationals had not explicitly agreed to uphold shadow cabinet solidarity, and that the Coalition could not proceed unless she was assured of this.

"It is not a new set of arrangements that fierce debates are had, both within party rooms and within and around the shadow cabinet table and the cabinet table. Having participated in many myself over the years, I know this.

"But then you come out as a united front, and you present a united agenda to the Australian people."

The Opposition Leader also said there was a pathway forward for the Coalition, despite the policy standoff.

"The Nationals' door remains open and our door remains open, and we look forward with optimism to rejoining at some point in the future."

The Albanese government is expected to hold 94 seats in the lower house when counting is finalised, leaving the Liberals with just 28 seats after losing more than a dozen in the party's worst electoral defeat in history, while the Nationals hold 15 seats after holding onto all but Calare.

Mr Littleproud dismissed a question about whether the Nationals could run candidates against the Liberals at the next election if talks did not resume, as "coming from ... a Canberra-bubble lens", saying the party would be "pragmatic".

Nationals Senate leader Bridget McKenzie left the door open to working with the Greens, which last year proposed legislation to allow the competition regulator to break up companies that exploit their supply chains, and independents when asked if this was on the table.

"The National Party has made no secret that they will work with anybody who will help us further the needs and interests of rural and regional Australia," she said.

Mr Littleproud also rejected the suggestion he was fighting "a losing battle" to revive the Coalition's nuclear plan, accusing Labor of "a scare campaign" while blaming former opposition leader Peter Dutton's abandoned policy to force public servants back to the office for the election result.

"We've got to be honest. It was about work from home," he said. "We saw that in regional electorates as well, where we copped a lot of the pain because of that.

But Mr Littleproud did not outline the Nationals' full position on nuclear, except to say it "must be part of the mix".

"We've always said we should have a technology-agnostic approach," he said.

"Whether that's owned by the Australian people, or ... taking the moratorium away, what we want to see is a mix in our grid."

Former Nationals Party leader and Riverina MP Michael McCormack said Ms Ley was "leading a party that is rebuilding" and that "this is a time of deep soul-searching for the Liberal Party."

"They can't govern without us and they also need to know that," Mr McCormack told the ABC on Tuesday.

Treasurer Jim Chalmers said the Coalition split was "a seismic event in our political history" that showed the Liberal and National parties had "learned nothing from the election result."

"They're focused inwardly on themselves," Dr Chalmers told reporters in Canberra. "The Albanese government is focused on governing."

Mr Littleproud said he wanted to resolve the impasse before the next federal election, saying the split was "a peaceful decision ... an opportunity to reset ourselves", but that "we're not going to put timelines or rush this," while noting that the 1987 Coalition split lasted four months.

"It might seem foreign to many in Canberra," he said. "I'm passionate in the belief that we can bring this back together."

Deputy Nationals leader Kevin Hogan likened the situation to a relationship break, telling reporters that "very often, more often than not, you get back together and you join back together with more clarity and more focus about what the relationship is, about what went wrong with it, about why you broke up and when you get back together, how it's going to work."

"We are always best as a country with a strong Coalition," Mr Hogan said.

"My wish in the future is that it's going to happen again sooner rather than later, but we needed to make, for us, a principled stand on things today that we could not move on."