Mr Littleproud met with Liberal leader Sussan Ley on Monday evening, with pressure mounting within the Nationals to end the messy coalition split.
The sit-down was the first formal reconciliation talk between the leaders since the break-up two weeks ago, triggered by a disagreement over hate crimes legislation.
Pressed on the issue on Tuesday morning, Mr Littleproud said there was ongoing work to bring the coalition back together but would not give a timeline.
"My room will make a determination, as we did a couple of weeks ago. There's no unilateral decisions," he told reporters outside a church service marking the official start of the parliamentary year.
But Scott Buchholz, a Liberal National Party MP from Queensland, appeared less optimistic about the chances of unity between the former political allies.
"That's where we need divine intervention," he said.
The Liberals and Nationals are expected to sit separately in the first question time since the political divorce.
The split was sparked by three Nationals senators voting against the government's hate crimes laws, despite a shadow cabinet agreement to support the bill.
Mr Littleproud blamed Ms Ley for the break-up, because she accepted the trio's resignations from the front bench.
All Nationals frontbenchers resigned shortly after, precipitating the dramatic split.
But members of the regional party are now publicly and privately calling for the coalition to get back together, to make it a more effective political force.
Queensland backbencher Colin Boyce failed to secure enough support to formally bring on a vote to spill the Nationals leadership during a partyroom meeting earlier on Monday.
Mr Boyce said the party needed to re-form the coalition, with a majority of MPs backing a separate motion introduced by Victorian MP Darren Chester to reinstate the political alliance.
The opposition leader will also likely face a challenge to her leadership of the Liberals this fortnight by Angus Taylor.
Polling has shown surging support for One Nation surpassing that of the coalition, causing alarm within both the Nationals and Liberals.
Ms Ley had previously handed down a one-week deadline to the Nationals for them to come back into the fold.
The Liberals planned to expand their shadow cabinet if an agreement was not reached by February 9, resulting in their takeover of frontbench roles held by Nationals.
The Nationals party room will hold a second meeting on Tuesday before the chambers sit at midday.
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