Barack Obama was told yesterday that his grandmother, who helped to bring him up through his teenage years, had died of cancer 24 hours before an election in which he may be elected president.

The Democratic nominee was extremely close to Madelyn Dunham, 86, whose personality shaped much of his life and who had watched every step of his campaign even though she had been extremely ill.

She died on Sunday night and Mr Obama was told yesterday morning while he was in Jacksonville, Florida. He went ahead with his final schedule of campaign appearances with the family saying a private ceremony will be held at a later date.

In a joint statement Mr Obama and his sister, Maya Soetoro-Ng, said: “She was the cornerstone of our family, a woman of extraordinary accomplishment, strength, and humility. She was the person who encouraged and allowed us to take chances.”

“She was proud of her grandchildren and great-grandchildren and left this world with the knowledge that her impact on all of us was meaningful and enduring. Our debt to her is beyond measure.”

Later, at an emotional rally in Charlotte, North Carolina, Mr Obama described her as “one of those quiet heroes we have all across America” for whom this election should be so important. Last month, the Democrat broke off the campaign trail for 36 hours so that he could fly to Hawaii and spend time with his ailing grandmother, whom he called Toot. Mr Obama said that he “got there too late” when his mother died of ovarian cancer in 1995 and had not wanted to “make the same mistake twice”.

His father, mother and maternal grandfather, Stanley Dunham are all dead. “My grandmother’s the last one left,” said Mr Obama on his return form Hawaii last month, adding: “I’m still not sure whether she makes it to election day. One of the things I want to make sure of is I had a chance to sit down with her and to talk to her.” She had been too ill to appear with her grandson in the election, but he spoke of her often, particularly at key moments such as in June when he clinched the delegates needed for the Democratic presidential nomination.

“Thank you to my grandmother who helped raise me, and is sitting in Hawaii right now because she can’t travel, but who poured everything she had into me, and who helped to make me the man I am today,” said Mr Obama, departing from his prepared text. “Tonight is for her.”

At the Democratic convention in August he spoke of how she became the first woman vice-president of her bank “despite years of being passed over for promotions because she was a woman”. He said: “She’s the one who taught me about hard work. She’s the one who put off buying a new car or a new dress for herself so that I could have a better life.”

He also cited Mrs Dunham as an example of old-fashioned attitudes towards race when he addressed the issue of his controversial black pastor, the Rev Jeremiah Wright, in Philadelphia in March. “I can no more disown [Wright] than I can disown my white grandmother,” he said.

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