John Hume has led the tributes to the wife of SDLP veteran Seamus Mallon, who died yesterday following a long illness.
Gertrude Mallon, who suffered from dementia, died at her family home in Co Armagh.
Seamus (80), a former Deputy First Minister, quit politics in 2005 to become his wife's primary carer after she started suffering from poor health.
It is understood the mother-of-one, who was a nurse and lifelong SDLP member, had been housebound at their Markethill home for the last number of years.
Mr Hume was among those who paid tribute to Mrs Mallon, describing her as the "beating heart" of the SDLP in south Armagh.
"She was a tower of support to Seamus, her contribution to peace, politics and people across this island is immeasurable," he added.
"It's often those closest to politicians who are forced to endure the most in difficult times.
"Gertrude's caring nature from her background in nursing stood her in good stead as she looked after not only her own family but all those who needed support as the horrors of that time unfolded."
Taoiseach Enda Kenny also paid tribute.
In a statement, he said: "It is with regret that I learned of the passing of Gertrude Mallon.
"I visited Gertrude and Seamus in their home last year in Markethill and saw first-hand the love and devotion they had for each other.
"Gertrude had been ill for some time and, along with her carers, Seamus demonstrated the commitment towards her in his personal life that was a central tenet of his public, political life."
SDLP leader Colum Eastwood said she was a lifelong SDLP member who "stood against violence alongside Seamus".
Mr Eastwood said: "Gertrude will long be remembered as a pillar of strength and a source of hope for SDLP members in Armagh during the darkest days of conflict, none more so than her devoted husband Seamus.
"Close family members of politicians often bear the greatest burden. And given Seamus's towering political stature and fierce opposition to violence in south Armagh, Gertrude and their child had a lot to bear.
"But it was her strength in the face of such visceral opposition, her unyielding commitment to peace and her unconditional support for Seamus that contributed as much to our political process as any negotiator."
Newry and Armagh MLA Justin McNulty said: "Gertrude made an outstanding contribution in her chosen profession of nursing and was a rock to her husband, Seamus, through the most difficult days of the Troubles here.
"She was a woman of courage who did not flinch even in the face of bomb and bullet. She will be sorely missed ... by all who loved and knew her."
In an interview with BBC Radio Ulster's Talkback programme last year, Mr Mallon revealed he often regretted not going for the party's leadership in 2001, but said he had a choice to make over Gertrude's health.
"I had to make a choice and I am confident that I made the right choice," he said.