Hours before what could be his most crucial moment, Obama lost his 86-year-old grandmother, who was battling with cancer.

The US Presidential nominee often described Madelyn Payne Dunham as a pillar of strength and the cornerstone of his family. It was Dunham who raised Obama. 

"She has gone home. She died peacefully in her sleep," said an emotional Obama at a rally in North Carolina.

The family said in a statement, "She was the cornerstone of our family, and a woman of extraordinary accomplishment, strength, and humility. She was the person who encouraged and allowed us to take chances."

Such was the affection that Obama took a break from campaigning last month and went to Hawaii to be with Dunham when her health deteriorated.

Image: Obama breaks down while speaking about his grandmother during a rally at University of North Carolina on Monday night.

Photograph: AFP/Getty Images