A spokesperson for Welsh Labour leader Rhodri Morgan has warned "Wales would become a laughing stock" if no deal was reached to form an assembly government.
Rhodri Morgan believes a deal is needed for stability
She said all the parties "can't be seen to have been unable to respond to the people's verdict" in the election.
Labour won 26 seats, five short of a majority, and is talking to the Lib Dems and Plaid about possible deals.
A first minister must be chosen by 31 May, so the chances of a formal coalition appear to be diminishing.
If AMs cannot agree who should be first minister a second assembly election would have to be called, something all the parties have said they want to avoid.
Labour believes that attempting to form an administration with no agreement with any of the other parties would not provide the stability needed at a time when the assembly has new powers.
Two of the six Liberal Democrat AMs, Mick Bates and Peter Black, and much of the party's grass roots are fiercely opposed to a coalition deal with Labour.
If Lib Dem leader Mike German was to agree a formal pact with Mr Morgan the deal could be thrown out by a special Liberal Democrat conference on 26 May, days before the deadline.
A full Labour-Plaid coalition is thought much less likely - such is the hostility between the two old political enemies.
Although not abandoning the prospect of a full coalition, Labour is exploring the possibility of more informal deals with its rivals.
It would prefer an arrangement with the Liberal Democrats but it could involve Plaid Cymru.
Such a deal would involve the rival parties agreeing to support Labour in critical votes in return for concessions in areas of policy.
The New Zealand government is run along these lines
The informal agreement might mean Lib Dem or Plaid AMs could even become the main assembly spokespeople on certain issues, housing for example, with access to civil servants.
But they would remain opposition parties, without seats around the cabinet table.
The next few days could be crucial.
One Lib Dem source told BBC Wales the leaders would have to "jump one way or the other" in the next 48 hours.