There has been speculation Edwina Hart AM would join the leadership race
Health Minister Edwina Hart has been urged by a senior colleague to stand as Welsh Labour leader when First Minister Rhodri Morgan stands down.
Finance Minister Andrew Davies ruled himself out of the running, but has now publicly backed Ms Hart for the job.
BBC Wales political editor Betsan Powys said Mr Davies's support was a signal that Ms Hart will stand, but she has not formally declared her plans yet.
AMs Carwyn Jones and Huw Lewis have already indicated they would stand.
Mr Morgan is widely expected to announce he is standing down as leader of the Labour group in the assembly at next weekend's party conference in Brighton, triggering a contest.
Each person needs to secure six nominations from their fellow AMs to be able to stand in the leadership race.
Betsan Powys said Mr Davies' intervention, the first by a senior figure in the party, signals the starting gun for what is likely to be a hard-fought contest between Ms Hart and Mr Jones.
Mr Davies, the AM for Swansea West, has been a minister since the Welsh assembly's inception in 1999 and his backing could be key for Ms Hart.
The likelihood of her standing will also deal a blow to the candidacy of the Merthyr AM Huw Lewis, according to Betsan Powys.
She explained that it is thought he has six confirmed backers among AMs, and one or more of them may now be tempted to defect to Ms Hart, leaving him short of the number needed to enter the contest.
I think people in Wales don't like the bland, they like someone with real strong decisive leadership, I think that is what Edwina has got
Finance Minister Andrew Davies AM
Ms Hart was Gower AM in the assembly's first election in 1999. She served as minister for finance and local government from 2000 to 2003. She was then appointed the minister for social justice and regeneration from 2003-2007, and became health minister in May 2007.
'Strong character'
Mr Davies said he believed Ms Hart had all the personal qualities and experience needed to be first minister.
"Very decisive, very clear leadership, massive experience in finance, local government, social justice and one of the biggest jobs of all in health," he said.
"And I think she has got the sort of character that people respond to, people like a strong character. That is why Rhodri has been such an effective leader and I think people in Wales don't like the bland. They like someone with real strong decisive leadership. I think that is what Edwina has got.
"She is a very effective team worker. She was president of the Wales TUC (Trade Union Congress). You don't get to that sort of level without the ability to work with people."
Mr Davies said he had been approached by senior figures inside and outside the Labour party for the previous three years about the leadership issue, but he decided not to run because he wanted to find a balance in his life.
"Given I had health problems last year, I had a blocked artery, and I had time off to reflect, I came to the decision that it wasn't something that I wanted to do.
"I know from my previous history that if I put all my eggs in one basket it is not good for me.
"Being first minister is a 24/7 job and I think it would mean an unbalanced life."
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