Entertainment Tonight

Barack Obama announced Monday that his ailing grandmother, Madelyn Dunham, has died. She was 86.

In a statement released to ET, Obama and his sister, Maya Soetoro-Ng, say:

"It is with great sadness that we announce that our grandmother, Madelyn Dunham, has died peacefully after a battle with cancer. 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. 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.

"Our family wants to thank all of those who sent flowers, cards, well-wishes, and prayers during this difficult time. It brought our grandmother and us great comfort. Our grandmother was a private woman, and we will respect her wish for a small private ceremony to be held at a later date. In lieu of flowers, we ask that you make a donation to any worthy organization in search of a cure for cancer."

Obama, the Democratic nominee for president, took a break from his campaign last month to visit Dunham. Obama's campaign spokesman Robert Gibbs said in a statement at the time, "Senator Obama's grandmother, Madelyn Dunham, has always been one of the most important people in his life. Along with his mother and his grandfather, she raised him in Hawaii from the time he was born until the moment he left for college. As he said at the Democratic Convention, she poured everything she had into him."