Under the plan to restore the coalition, the Liberals would regain the assistant treasury portfolio - a role previously held by the Nationals - and hand the skills portfolio to the regional party in exchange.
But the Nationals are yet to accept the deal after weeks of political infighting.
The rural party wants Bridget McKenzie, Ross Cadell and Susan McDonald, who resigned from their portfolios after breaking with shadow cabinet on Labor's hate speech laws, to be returned to their jobs.
Ms Ley told her party room on Tuesday she offered Nationals leader David Littleproud a deal to restore the coalition if the trio remained on the back bench for six months after crossing the floor.
The opposition leader gave the Nationals an ultimatum to rejoin the coalition before Monday, when the second sitting week of the fortnight starts.
Liberals acting in shadow cabinet portfolios would be given permanent posts to replace their former colleagues if that deadline is not met.
Mr Littleproud confirmed an offer had been made but wouldn't reveal his party's next steps.
"We will take our time to consider the details," he said.
"The Nationals are united in our endeavours to reset the coalition, but we won't be providing updates on any negotiations through the media."
The regional party wants to relax shadow cabinet rules so its frontbench MPs can vote separately from the Liberals.
But the Liberals are reluctant to water down solidarity restrictions, with Ms Ley telling her party room the principle would be reaffirmed as part of any reunion deal.
The two party leaders met on Monday evening as pressure mounted within the Nationals to end the messy coalition split.
Pressed on the issue on Tuesday morning, Mr Littleproud said work was under way to bring the coalition back together but he would not give a timeline.
"My room will make a determination, as we did a couple of weeks ago," he told reporters outside a church service to mark the official start of the parliamentary year.
"There's no unilateral decisions."
Ms Ley said their discussions had been constructive.
"At this point, the door is open; I have maintained that the door stays open," she said.
Scott Buchholz, a Liberal MP from Queensland, appeared less optimistic about the chances of unity between the former political allies.
He joked it would take an act of providence for the estranged political parties to reunite as allied and rival MPs met for the religious service.
"That's where we need divine intervention," he said.
Multiple members of the regional party have been publicly and privately calling for the coalition to get back together to make it a more effective political force.
