The vote could be another step on the path to greater Senedd powers
An agreement has been reached that means all four parties in the Welsh assembly will now support a "trigger" vote on a referendum on further powers.
Both the Conservatives and Liberal Democrats had threatened to abstain over concerns about holding a vote on the same day as an assembly election.
But BBC Wales understands First Minister Carwyn Jones will now acknowledge that strength of feeling.
He will say his government will work to accommodate those concerns.
The vote next Tuesday will be drafted to facilitate a "trigger" for the referendum process.
Welsh Liberal Democrat leader Kirsty williams says her party will not block a referendum vote
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.
If next week's trigger vote is passed, Mr 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.
The Tories and Lib Dems had both said that they would 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 have meant falling short of the 40 votes needed to pass the trigger vote.
But BBC Wales political editor Betsan Powys said the compromise had ensured the trigger vote will now be carried.
"While no guarantee's been given that the referendum will not be held on the same day as the assembly election, the acknowledgement that it's a difficult area seems to have been enough to reach agreement between all four party leaders.
"The Conservatives say they'll come to a final decision on how to vote on Tuesday. This will be a free vote for the Conservative group.
"But BBC Wales understands that most Tories are pretty happy with the agreement.
"The Liberal Democrats too are pleased that things can now move forward on an all-party basis," she said.
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