The Conservative group leader in the Welsh assembly, Nick Bourne, has confirmed he has held talks with Plaid Cymru about forming an administration.
The Tories would want cabinet seats as part of any deal
He said his party was only interested in a coalition with Plaid and the Lib Dems, ruling out a "stability" pact.
Mr Bourne said early talks focussed on how many Conservative manifesto pledges could be delivered in a coalition.
Labour, the largest party, is five seats short of a majority and seeking Lib Dem or Plaid help to stay in power.
After an hour-long meeting of Conservative AMs, Mr Bourne made it clear he was not willing to help other parties take power in Cardiff Bay unless the Tories had seats around the cabinet table.
He said: "We Conservatives do government and sometimes we're obliged to do opposition but we don't do limbo.
"There's no question of a so-called 'stability pact'. I don't think it would be stable and I don't think it would be a pact so we don't want any part of that."
Under a "stability pact" an opposition party agrees to keep an administration in power in return for some of its policies being taken up, but without joining the cabinet.
Following the 3 May assembly election, the Conservative group of AMs is now 12 strong, Labour has 26 seats, Plaid 15 and the Lib Dems 6.
Plaid Cymru said on Wednesday it would decide next week whether to try to lead the assembly government.
Much to gain
Party leader Ieuan Wyn Jones said Plaid was talking to Tories and Lib Dems to see if it could force Labour from office, but stressed that discussions continued with Labour.
But Welsh Secretary Peter Hain indicated that he did not support any sort of deal between Labour and Plaid Cymru.
Peter Hain is not keen on a deal with Plaid or the Tories
Asked by BBC Radio Wales whether his party could do a deal with Plaid or the Conservatives, Mr Hain replied "certainly not".
He told the Good Evening Wales programme that it was "no secret that the mood of Labour in the assembly and throughout the party is for a deal with the Liberal Democrats rather than any other arrangement".
Mr Hain suggested that the Lib Dems and Labour had much to gain from joining forces.
He said: "I think there is a prospect of a very good agreement for stable government in which the Liberal Democrats will get some gains in which they'll have the opportunity to influence policy.
"But if they want to go to bed with the Tories and the Welsh nationalists, well that is a matter for them."
Later, Mr Hain's spokesman moved to clarify his remarks, saying that it was not his intention to rule out any such deal - "that's a matter for Rhodri Morgan, the leader of Welsh Labour".
He said Mr Hain was insisting that "certainly not" on the cards was any kind of deal between Plaid and the Tories, for which he said there was "no electoral mandate".
The Liberal Democrat national executive and group of AMs are meeting in Llandrindod Wells later.
They are expected to ask a new negotiating team to identify one or two options and to work towards a deal that would be acceptable to the party as a whole.
An assembly government must be formed within 28 days of the poll to avoid a new election.