TUC leader Brendan Barber is stepping down at the end of the year, leaving job observers betting that his deputy Frances O'Grady will be the first female general secretary.
After 61-year-old Mr Barber, a father of two, told the TUC executive committee of his decision it paved the way for his successor to be elected at this year's TUC Congress in September.
He said today: "I have decided that this is the right time to make a change in my life. I have been enormously privileged to work at the TUC since 1975 and the end of the year will mark the 10-year point since my election as general secretary.
"I have every confidence that under new leadership the TUC can go from strength to strength."
TUC president Paul Kenny said: "Brendan has made an immense contribution to the trade union movement and has been one of the most successful TUC general secretaries.
"I hope he will continue to make a huge contribution to the movement after he leaves the TUC. He will be duly honoured by affiliates at the Congress."
He became general secretary in May 2003 when John Monks left the TUC to become general secretary of the European TUC.
Favourite to succeed Mr Barber is Ms O'Grady, who has been an active trade unionist and campaigner all her working life.
She previously worked for the T&G union before joining the TUC as campaigns officer in 1994.
The TUC's 54 affiliated unions can put forward candidates. If there's more than one, there'll be voting at the Congress.
Sources close to Mr Barber said when he retires he'll probably be playing more golf and taking an even keener interest in his favourite football team Everton.
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