Outspoken opposition MHK Peter Karran has announced that he will not seek re-election in September.
The Onchan MHK and LibVan founder said that he will be standing down after more than 30 years in public office.
In a letter to constituents, Mr Karran wrote: ‘I feel now the time has come for me not to seek re-election at the next General Election.
‘It’s time for me to give someone else the opportunity to serve you; for someone else to take on the challenge of standing up, in our Parliament, for those who need to have truth spoken to power - and to oppose what must be opposed.’
Mr Karran said that his record ‘speaks for itself’.
‘I have, for over 30 years, done my very best to show the people of the Isle of Man the true facts relating to Government’s actions,’ he wrote.
‘I have often been a lone voice speaking out against policies and projects that have proved to be wasteful of public funds.’
LibVan leader and Douglas South MHK Kate Beecroft said: ‘Peter started the Liberal Vannin Party in 2006.
‘He is the reason that I joined the party and I have worked with him since then.
‘To say that he will be greatly missed is a real understatement.’
Mr Karran said that he will continue to work for the LibVan Party.
In a extraordinary side swipe at fellow Onchan MHK Zac Hall, who was expelled from LibVan in 2012, Mr Karran told constituents: ‘I offer a sincere apology to those of you who voted, at my behest, for Zac Hall.
‘I don’t always get things right.
‘It is my opinion that when he had his LibVan party membership withdrawn, he ought to have organised his affairs and resigned his seat.’
Mr Karran has held many parliamentary roles during his political career including Education Minister in 2011-2012 and chairman of the Water Authority from 1990 to 2003.
He was first elected to the House of Keys for Middle in a by-election in 1985 at the age of 25, having unsuccessfully stood for the same seat in 1981.
He has been re-elected as MHK for Onchan in 1986, 1991, 1996, 2001, 2006 and 2011.