Plaid Cymru AMs will decide which coalition deal they favour in the next "seven to 10 days", the party's leader Ieuan Wyn Jones has said.
Ieuan Wyn Jones is waiting for discussions with Labour to finish
The party is negotiating with Labour over a possible deal, but could still opt for a so-called rainbow alliance with the Tories and Lib Dems.
Mr Jones said the assembly group would decide soon on which plan to recommend.
Lib Dem assembly leader Mike German said he would consider a deal with Labour if the rainbow bid was failing.
However, Lib Dem AM Eleanor Burnham said that Mr German did not have a mandate to enter new discussions with Labour and that the party's national executive and national council would have to be reconvened for that to happen.
Speaking on BBC Wales about the two options facing Plaid, Mr Jones said the party was waiting until discussions with Labour had finished before making a decision.
"It'll take a few more days I think for that document to be completed and then I think we can make a proper judgement between the two," he said.
Rhodri Morgan said talks with Plaid would resume on Monday
Mr Jones said no more work was needed on the All Wales Accord document for the rainbow deal but that "there is still more work to do on the Labour document".
He said Plaid had reopened discussions with First Minister Rhodri Morgan after Labour asked them "to consider some further matters" which had not been included in earlier proposals for a stability pact.
"Clearly there are things that were not in the stability pact which are now in, which obviously put it in a different league," he said.
However, he would not give more details on whether the Labour deal included a referendum on more assembly powers or cabinet posts for Plaid AMs.
He said it was "inevitable" that there would only be one preferred option before the party's grassroots met in a national council on 7 July.
Mr German said his preferred option was the rainbow alliance, but that he hoped it would not be "shipwrecked".
"We need to know if the contract we have signed up to with Plaid Cymru is one which they are going to continue," he said.
He said his party would have a different decision to take if he sensed a change of direction by his rainbow coalition partners.
He said he had already had a short preliminary discussion with Rhodri Morgan on key issues, but that he would only reopen negotiations with Labour if the rainbow alliance was failing.
Speaking on his blog, Peter Black AM said soundings had already been taken within the Lib Dems as to what they should do if the possibility of a rainbow coalition faded away.
A spokesperson for Welsh Labour leader and First Minister Rhodri Morgan said meetings with Plaid would resume on Monday, ahead of Labour's own special conference on 6 July.
Welsh Tory leader Nick Bourne said he remained confident his party could secure "the necessary support across all three opposition parties for a non-Labour coalition government in Cardiff Bay".