Nuclear energy has blown up a political agreement between the Nationals and the Liberals after leaders failed to reach common ground but left the door open for a reconciliation.

The traditional political marriage couldn’t be consecrated following a disastrous result for the Coalition at the federal election with the Nationals standing firm on wanting to retain four key policies.

These included remaining committed to nuclear energy, divestiture powers to break up big supermarkets, a $20 billion investment fund that would disperse $1 billion a year on regional infrastructure and universal phone services.

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Landlines and payphones must have service no matter where they are in Australia but this doesn’t extend to mobile phones, which the Nationals have been fighting to include.

Nationals Leader David Littleproud said the party didn’t want to have to re-prosecute the case to retain the policies it fought for under the previous agreement in opposition.

“It’s on a principled position of making sure that those hard-fought wins are maintained and respected and we continue to look forward,” Littleproud told reporters in Canberra on Tuesday.

Opposition Leader Sussan Ley addressed the media in the afternoon, emphasising her commitment to the Coalition despite the recent split.

“I really believe that the Coalition is stronger together, I am a committed Coalitionist,” she said.

“I do pay tribute to my Liberal Party colleagues in this room now and their intention to work constructively for the future with new and different policies, but never stepping away from our timeless values.

“Our policies may change, our values never will. But we need to give that process due diligence and I, as leader, want to harness the real initiative, interest, talent and the smarts of so many.”

Ley also acknowledged there were significant roadblocks to a unified Coalition.

“Shadow cabinet solidarity is very important and unless I, as leader of the Liberals, could be sure about that, it was important that we didn’t take those next steps,” she said.

“As I’ve said, I wasn’t assured of that with issues that may divide both members of their party room and members of our party room in the future.”

“The Liberal party’s door remains open to the Nationals’ should they wish to rejoin the coalition before the next election.”

Liberal sources say the National party gave Ley less than an hour’s notice of their decision.

The change in opposition doesn’t have a substantial impact on the government’s ability to pass legislation with Labor commanding a major majority in the lower house and only needing the Greens in the Senate.

The Liberals still have the numbers to pass legislation in the Senate with Labor without the Nationals.

Without a Coalition agreement, Labor has a significant electoral advantage with the Liberals holding fewer than 30 of 150 lower house seats and the Nationals, 15.

The Nationals won’t sit in shadow cabinet, meaning they won’t hold sway over policies and the half-dozen MPs who were around the table will take a pay cut.

The Coalition last broke up in 1987 for about four months.

Littleproud left the door open for a future arrangement, saying the two parties would still work together to fight the Labor government.

Opposition Leader Sussan Ley faces the task of rebuilding the Liberals after a wipeout at the May 3 election.

The break-up would give Ley the time and space she needed to rebuild her party, Littleproud said.

“They are going on a journey of rediscovery and this will provide them the opportunity to do that without the spectre of the National Party imposing their will,” he said.

Littleproud denied the Nationals were a drag on the Liberal vote in the inner cities.

Their policies were popular, especially in their regional seats, and others such as the push to scrap public sector working from home entitlements - spearheaded by Liberal senator Jane Hume - were electoral poison, he said.