Welsh Labour leaders have agreed to hold a special conference to discuss an assembly coalition with Plaid Cymru.
Rhodri Morgan leaves the executive meeting with colleagues
The Welsh party's national executive met after First Minister Rhodri Morgan offered a deal to Plaid to support his minority assembly government.
Party chairman Tecwyn Thomas called it a "momentous point" for Labour and politics in Wales.
The conference will be on 6 July - the day before Plaid holds its own special conference to discuss the deal.
First, however, Plaid will meet on Saturday in Aberystwyth to examine the Labour offer - as well as another possible coalition with Conservatives and the Liberal Democrats.
The latest steps come after Labour fell five seats short of an outright majority in last month's election.
Although Mr Morgan was reinstalled in the top job, he could be forced out if Plaid team up with Conservatives and Lib Dems to form a "rainbow alliance".
Mr Morgan, who said he was "between a rock and a hard place", turned to Plaid after the Lib Dems pulled out of talks with Labour.
Welsh Labour chairman Tecwyn Thomas said: "This is a momentous point in the history of Welsh Labour and the politics of Wales," and his party had to "act responsibly in the interests of the people."
He said: "With such a major and vital decision facing the Labour Party and Wales, the executive feels it is right and proper that the wider party be consulted in the fairest and most open way possible."
He said the conference would "allow the membership of our party and party affiliates to have their say."
The Labour executive will also meet before 6 July to make a recommendation to the special conference.
The trade unions will have a big say in Labour's final decision, and senior union figures have predicted they will back the Plaid deal.
Delegations from unions in Wales would control between 50,000 and 80,000 votes, which would almost certainly swing the decision one way or the other.
'Compromise and commitment'
Bill King, the Unison convenor for Wales, said he could see "no reason" why a Plaid-Labour deal could not last for four years, providing there was reasonable compromise and commitment.
"What we need is a sustainable government in Wales that is actually going to deliver policies that will benefit the people from Wales and if that means going into coalition, then that's what we have to do," he said.
Cath Speight, the regional secretary of Amicus, which is the largest affiliate to Labour in Wales, said she could understand if some members were uneasy about a coalition, but Labour had to remain in power.
"I think the most important thing is for our members is that we deliver as much of the Labour party manifesto as is possible in the next four years," she said.
Plaid leader Ieuan Wyn Jones could take a seat in the cabinet
"The damage that could be done by the rainbow coalition in four years in power, I don't think that's a price that my members would be willing to pay."
Earlier, Mr Morgan said he was concentrating on finalising a deal with Plaid, but his door was still open to Lib Dems.
Speaking to BBC Wales' Dragon's Eye programme, Mr Morgan said he felt only a "tiny minority" of his party believed Labour's future would be best served in opposition.
Mr Morgan said he was duty bound to implement the Labour party's manifesto, "even if it is at the price of implementing somebody else's manifesto as well".
"In terms of the attitude of the Labour Party, they all understand that we are between a rock and a hard place and that there is a tiny minority that probably does believe in walking away, but I think that's a tiny minority," he said.
"I think the majority say... we must not allow the Tories to get back into a position of being ministers looking after public services in Wales."
Mr Morgan said it was up to Lib Dem assembly leader Mike German to contact him if he wanted to reopen the door to negotiations.
He confirmed he had discussed the way ahead for Labour in the assembly with Prime Minister-in-waiting Gordon Brown, but refused to elaborate on those talks.