MP Ivan Lewis has vowed to "carry on regardless" despite revelations about his private life.
The Labour minister (39) admits his marriage of 16 years is over, and he and his wife Juliette are getting a divorce.
But he refused to comment on reports that he has been having a relationship with a married Prestwich councillor, Maggie Gibb.
Mr Lewis said it was "up to other people" what they thought of the allegations, and he would continue to do his best for his constituents.
The Bury South MP has left the family home in Prestwich which he shared with Juliette (46) and his two sons, aged nine and 11. He is now living with his father elsewhere in Prestwich.Since being elected in 1997, Mr Lewis has been an education minister, economic secretary to the Treasury, and now is minister for care in the department of health.
He is widely tipped to return to the Treasury if Gordon Brown becomes party leader.
"I've been separated from Juliette for five months, and we are arranging a divorce," said Mr Lewis. "Past that, I'm not prepared to go. Everyone has a right to speculate and to gossip, but I also have a right to privacy, and that's it. I will continue to live in the constituency and work hard on behalf of my constituents, and focus on the issues that affect their day to day lives."
Labour councillor Maggie Gibb (50) is a clinical psychologist in Rochdale, and has represented St Mary's ward in Prestwich for the last three years. She holds a senior post on Bury Council, as executive member for children and young people. She declined to comment.
Asked whether people would think less of him, Mr Lewis replied: "That's for them to decide. It won't affect my commitment and my sense of responsibility to make Bury South a better place. People know how committed I am and how much I believe in what I am doing to improve people's lives. I've had a lot of support and friendship from local people, both myself and for my family. That's been nice, and I thank them for that."
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