Rhodri Glyn Thomas Plaid Cymru AM to stand down in 2016
Plaid Cymru AM and former Heritage Minister Rhodri Glyn Thomas has announced he will stand down at the next Welsh assembly election.
He has been a member of the assembly since it was established in 1999.
Mr Thomas will have represented Carmarthen East and Dinefwr for 17 years by the next election in 2016.
He had a 4,148 majority over Labour in 2011 and his departure will fuel speculation on whether other well-known Plaid figures will try to replace him.
BBC Welsh affairs editor Vaughan Roderick said the vacancy could attract interest from other leading Plaid figures, such as the former local MP Adam Price, or former AMs Nerys Evans and Helen Mary Jones.
Mr Thomas was one of three Plaid cabinet members when the party went into coalition with Labour in 2007.
But he resigned the following year after being seen walking into a pub with a lit cigar, after smoking in public places had been banned.
That came shortly after he read out the name of the wrong winner at the Wales Book of the Year award ceremony.
He is Plaid's spokesman on local government, housing and transport, and last year was heavily critical of Labour's handling of council tax benefit.
Plaid has begun the process of selecting candidates for the next assembly and Westminster elections.
Mr Thomas said: "As the party continues to go through its period of renewal and prepares for an assembly majority, I believe it is the right time to select a new candidate for that election.
"I am very grateful to party members and to the voters of Carmarthen East and Dinefwr for their continued confidence. I am very proud to have had the opportunity to represent this constituency.
"I have decided to make this decision now to allow the local party to select a new candidate and give that candidate the best possible chance to achieve a successful result in 2016."
Plaid leader Leanne Wood said: "As one of Wales's first assembly members, Rhodri's experience and passion for his Carmarthenshire constituency makes him a formidable force in Welsh politics.
"He has served his constituents and Plaid Cymru with dedication for many, many years. I'd like to take this opportunity to thank Rhodri for his sustained effort in our attempts to make Wales a more prosperous place."