A Welsh assembly vote next week will enable AMs to "trigger" the process for a referendum on further powers.
The Welsh Labour and Plaid Cymru leaders, Carwyn Jones and Ieuan Wyn Jones, have confirmed it could begin the process towards the referendum.
The vote on Tuesday, 9 February will be drafted to facilitate the so-called "trigger," but the assembly government is not sure of the 40 votes it needs.
Both Conservatives and Liberal Democrats say they could abstain.
A Yes vote in a referendum on full powers in devolved areas would enable the assembly to make laws in areas it already has responsibility for without seeking the approval of the UK parliament. Such policy areas include health, education, transport and the environment.
If next week's trigger vote is passed, First Minister Carwyn Jones will notify Welsh Secretary Peter Hain of the assembly's wishes within 14 days by letter.
Mr Hain would then have 120 days - or until 9 June - to lay a detailed draft order for a referendum, to be voted on by both houses of Parliament.
We believe we could do even more for the people of Wales if all new laws in the areas that are currently devolved could be made here by the assembly
First Minister Carwyn Jones
But both Tories and Lib Dems have reiterated that they will not back the trigger vote unless they get an assurance that the referendum will not happen on or around the assembly election day in May 2011.
That would mean falling short of the 40 votes it needs to pass the trigger vote. A meeting of the four party leaders is scheduled for Tuesday afternoon.
Both Labour and Plaid say they are not prepared to rule any dates in or out, and senior sources are adamant that no date has yet been chosen.
Carwyn Jones said: "We believe we could do even more for the people of Wales if all new laws in the areas that are currently devolved could be made here by the assembly."
The Welsh Labour leader said he would anticipate that any campaign for a Yes vote would "start in earnest after the general election," which has to be held by June at the latest.
He said it would be important that people understood the nature of the question asked in the referendum and that proposing that question would be an "unenviable" job for the Electoral Commisssion.
A two-thirds majority of AMs will be needed to carry the "trigger' resolution, which means 40 or more votes.
Attention will now focus on the likelihood of that vote being successful, given that, with two AMs on long-term sick leave, the Labour-Plaid coalition can only count on 36 votes.
Carwyn Jones said the matter of whether opposition parties would support the trigger motion on 9 February was a matter for them.
He added that he welcomed reports that the Liberal Democrats would back the motion. He added: "As regards the Conservatives, you have to ask them what their position is."
Many people believe it's the assembly and the the assembly government which should have the most influence over the people of Wales and we're moving in that direction
Plaid Cymru leader Ieuan Wyn Jones
Deputy First Minister Ieuan Wyn Jones said: "Many people believe it's the assembly and the the assembly government which should have the most influence over the people of Wales and we're moving in that direction.
"The opportunity that arrives for us under the Government of Wales Act, with the opportunity for a referendum means that we can do a lot of things more efficiently."
The Plaid leader said the timing of the 9 February vote meant that "it keeps all options open...that will mean there may be a referendum in the autumn or it may be next year."
He said support for the trigger motion "doesn't tie you to a particular date or rule anything in or out".
The reason for any doubt about the vote being carried is that, though the Conservatives and Liberal Democrats both support a referendum, each is concerned about when it would take place.
They want assurances that the referendum would not coincide with the period around the next assembly election on 5 May, 2011.
Lib Dems reacted to the announcement by saying that despite their "100%" commitment to a referendum, they will abstain on the trigger vote if the referendum is not ruled out on or near that date.
The Conservatives have also said they will abstain without such assurances from the Government.
Both oppose any possibility of fighting a referendum campaign on further powers at the same time as an assembly election.
They are against what they fear would be a confusing situation where politicians would be attacking each other as part of the election campaign, but uniting elsewhere around the referendum issue.
The question of the timing of any referendum remains highly uncertain.
Even if all parties agree that an autumn 2010 referendum would be preferable, the pressures of parliamentary time, and uncertainties around a general election mean it may not be deliverable.
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