Peter Hain has told ITV News he will "play a different role" in politics after he steps down as MP for Neath next year, but refused to say what that role would be.
The 64-year-old former Welsh Secretary said he had made his decision to leave the House of Commons after discussion with Labour leader Ed Miliband.
Mr Hain said he will "continue to be active in politics", supporting Labour and Neath.
Asked whether he would become a member of the House of Lords, he said: "I'm not talking about any particular role I might perform."
Mr Hain told our reporter Tom Sheldrick that his early work in fighting apartheid, delivering extra powers for the Welsh Assembly and helping secure a political settlement as Northern Ireland Secretary were "the things I feel most proud about".
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A dry start with some cloud in across the west. There will be plenty of sunshine throughout the day and it will feel warmer than Sunday.