Huw Jenkins has stepped down as chairman of Championship club Swansea City.
Jenkins, 55, was appointed chairman in January 2002 and oversaw a huge reversal in fortunes.
The club almost dropped out of the Football League in 2003 before rising up the divisions to win Premier League promotion in 2011.
"It comes with great sadness but I feel I've been left with little or no option [but] to leave my position," he said.
But Jenkins has been criticised by some Swansea supporters since the takeover of the club in 2016 by American pair Jason Levien and Steve Kaplan,
Calls for him to step down intensified since the club's relegation to the Championship last season.
On Saturday, Swansea City Supporters' Trust criticised the club's owners for lacking ambition and called for Jenkins to stand down.
It came in the wake of a January transfer window in which the club lost further players and made no signings.
"Swansea City has been a massive part of my life from a very young age," Jenkins added.
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Huw Jenkins had come under increasing criticism from some sections of Swansea City supporters
"I have been very fortunate to fulfill my childhood dreams over the last 17 years or so providing direction and leadership at the club whilst moving through the football leagues and competing with the elite of British football in the Premier league for seven seasons.
"Gradually over the last few seasons my role as Chairman providing such leadership and direction has been eroded away.
"Finally I can sit back no longer and hide behind my position and stay true to myself and my beliefs."
Swansea spent seven seasons in English football's top-flight and the club won the Football League Cup in 2013 and qualifying for the Europa League.
"To have lead our football club through the greatest period in the clubs history has been a fantastic experience," Jenkins added.
"The atmosphere that we created within the club was without a doubt one of the key factors to our success over many years.
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Steve Kaplan (centre) and Jason Levien (right) decided to keep Huw Jenkins (front left) as chairman when they bought a controlling stake in Swansea City in July 2016
"The directors and staff that worked with me over the last 17 years supported me with total trust and loyalty and we all shared a true Love for Swansea City and we operated like true supporters to run the club from top to bottom."
Jenkins was lauded for the managerial appointments of Roberto Martinez, Brendan Rodgers and Michael Laudrup during his time in charge of Swansea, which also saw the club move to the Liberty Stadium
"Sound managerial choices helped me build the football club and with the working relationships I developed provided our football club with a solid platform to achieve unrivaled success over many of those earlier years and that's one of the things l shall miss most about my time as chairman.
"I would like to thank all the staff and players past and present and the clubs supporters who have supported me fully over the last 17 years.
"It has taken me some time to finally come to this decision but the current atmosphere with in the football club on and off the football field saddens me very much and I find it very difficult to fight on in a football club I love but can no longer control."