The Papua New Guinea Supreme Court in Port Moresby is today expected to consider an application to overturn the re-appointment of Sir Michael Somare as leader of the National Alliance.
The NA is presently forming a coalition which it hopes will ensure it is restored to government on Monday when Parliament sits.
But the leaders of a rival coalition, headed by former prime ministers, Sir Mekere Morauta and Sir Julius Chan, filed a legal application yesterday, saying the NA has not complied with its own constitution.
Our correspondent in PNG, Alex Rheeney, has more.
"What they are indicating is that immediately after the return of the writs [on Monday last] the National Alliance should have had a national convention to elect its parliamentary leader and that was not done. They are trying to get the Supreme Court to basically rule that Sir Michael's re-election was not in line with the party constitution."
Meanwhile the NA claims to now have the backing of 81 of the 109 MPs.