A standing ovation given to Mo Mowlam during a key Labour party conference speech by Tony Blair led to a campaign against her, her husband has said.
Mr Norton said 'adverse stories' appeared after the ovation
In her autobiography, the late Northern Ireland secretary said she was "knifed in the back" because of her popularity.
Her husband Jon Norton told BBC One's Sunday AM programme the problems started after the PM's speech at Labour's 1998 party conference.
Mr Norton was speaking ahead of a tribute concert for his wife in London.
Ms Mowlam died in August aged 55.
Speaking of the ovation, Mr Norton said: "It was certainly the beginning of adverse stories in the paper after that.
He added: "I remember we had [US Secretary of State] Madeline Albright visit us just after that and she was warning Mo that that was probably the most dangerous thing that had ever happened in her political career."
Mr Norton was speaking ahead of a memorial event at the Drury Lane Theatre on Sunday night.
Celebrities set to appear include comedians Paul Merton and Patrick Kielty.
Ms Mowlam oversaw talks which led to the 1998 Good Friday Agreement
Lulu will sing to close the event.
Mr Norton said he expected about 2,000 people to attend.
Ms Mowlam, Labour MP for Redcar between 1987-2001, oversaw the talks which led to the 1998 Good Friday Agreement.
In 1999 she was replaced as Northern Ireland secretary by Peter Mandelson, and became Tony Blair's cabinet "enforcer" after turning down the job of health secretary. She stood down as an MP in 2001.
A former key ally of Mr Blair, who helped organise his leadership bid in 1994, she became increasingly disaffected with his premiership and was a vocal opponent of the war in Iraq.