By Brian Meechan BBC News

Rhodri Morgan will stand down when he reaches 70

Rhodri Morgan is celebrating eight years at the helm of the assembly government. He'll be forgiven for reflecting on his achievements and considering his legacy.

But on Friday, he told us that he plans to stand down as First Minister on or around his 70th birthday on 29 September, 2009.

Ambition is in the DNA of most politicians and there will be many Labour assembly members with an eye on the prize of leading their party and the nation as well.

But some senior cabinet figures have already ruled themselves out. Health Minister Edwina Hart and Environment Minister Jane Davidson are experienced hands who've been seen as credible candidates for the job. Both have said they won't stand.

Carwyn Jones is the heir apparent, according to some political watchers

Welsh Labour has prided itself on having more women assembly members than men. It's one of the reasons why the Welsh assembly had an equal gender balance - one of the few institutions in the world that had - though that's no longer the case.

But for a party that celebrated its role in bringing gender balance to Cardiff Bay politics, the runners and riders more usually talked about for the leadership are an exclusively male group.

The Counsel General, who's the chief legal adviser to the assembly government, Carwyn Jones is - some say - the heir apparent. He was agriculture minister at the time of the foot- and-mouth outbreak in Wales and he's considered a safe pair of hands and a good communicator.

Finance Minister Andrew Davies is responsible for public service delivery. He's seen by some as more managerial in style than his colleagues and as someone able to get the job done.

Leighton Andrews is seen as a strong campaigner

Deputy Minister for Regeneration Leighton Andrews became an assembly member in 2003, unlike Carwyn Jones and Andrew Davies, who've been ministers since 1999.

But he's seen as a strong campaigner. He may be less likely to run if Andrew Davies is a candidate because they previously worked together in business and could appeal to the same constituency.

Merthyr Tydfil AM Huw Lewis, was the former deputy social justice minister. He spoke out against Labour's coalition deal with Plaid Cymru and was subsequently left out of the government when the parties formed a coalition in the assembly.

He may appeal to the section of Labour's rank and file who are unhappy with that deal, if he can get the six nominations from assembly members that are needed to get on the ballot.

As the clich� goes, a week's a long time in politics, which means there's an awful lot that can happen in the next 18 months.

We can expect plenty of positioning and even more speculation before September 2009.