Jane Davidson has served as both education and sustainability minister
Sustainability Minister Jane Davidson has confirmed she will not stand for re-election to the Welsh Assembly at the next elections in 2011.
The Pontypridd AM told local officials her decision on Friday night
In a statement Ms Davidson said she had been "immensely privileged" in her career, but that 2011 was the "right time for me personally to step aside".
She was once tipped to succeed Rhodri Morgan as first minister when he quits the role next year.
Ms Davidson also served as education minister in the assembly government from 2000 to 2007.
She has been sustainability minister since July 2007 in the Labour-Plaid Cymru coalition government.
The politician issued a statement confirming her decision on Saturday.
She said: "I am immensely privileged to have been elected the AM for Pontypridd on three occasions and to have held two ministerial posts in the Welsh Assembly Government.
"In a small legislature like the assembly, I believe that it is important that people should be able to move in and out of life as politicians to renew our democracy.
"I believe that 2011 is the right time for me personally to step aside and move onto a new challenge for the rest of my working life."
Ms Davidson added she would continue to be an active member of the Welsh Labour Party.
She said she would also campaign for further devolution of powers and added she was particularly looking forward to having more time for walking and cycling.
She was one of the original Labour assembly members when the devolved administration was set up in Cardiff Bay 1999.
Haydn Jones, Pontypridd constituency Labour party chair, thanked the AM "for her tireless efforts in campaigning on local issues"
He added: "In particular, we know that we would not have won the Church Village Bypass without her which is so important to our constituency and we know that she will be actively supporting the regeneration of Pontypridd until 2011."
Mr Jones said she had been a "very effective minister" and had done a great deal locally to increase support for the assembly.
When Rhodri Morgan revealed he would stand down as first minister when he is 70 in September 2009, Ms Davidson was one of those tipped to succeed him.
Jane Davidson is married with three children and lives in Gwaelod y Garth, near Cardiff.
Educated at Malvern Girls' College, Birmingham University and the University of Wales, she was a teacher in Cardigan and Pontypridd before entering politics.
She is also an experienced youth and community worker and former Cardiff councillor.
She previously worked for the Youth Hotel Association in Wales, ran an anti-poverty organisation and was responsible for health, housing and social care for the Welsh Local Government Association.
Before entering the assembly Ms Davidson managed Mr Morgan's parliamentary constituency office.