Democratic presidential candidate Barack Obama says he's not sure his gravely ill grandmother will live to see Election Day.

Obama flew to Hawai'i to visit Madelyn Dunham, 85, who helped raise Obama. The Illinois senator said he left the campaign trail with less than two weeks remaining before the election because his grandmother is ill but alert. Her brother has said she recently fell and broke a hip.

"Without going through the details too much, she's gravely ill. We weren't sure and I'm still not sure whether she makes it to Election Day," Obama told ABC's "Good Morning America" in an interview broadcast today.

"We're all praying and we hope she does, but 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's still alert and she's still got all her faculties. And I want to make sure that I don't miss that opportunity," he said.

Obama has said he missed a chance to visit his mother just before she died of ovarian cancer — she was 53 when she died in 1995 — and didn't want to repeat that mistake. Dunham, whose birthday is Sunday, was staying at her Honolulu apartment.

At a rally yesterday in Indianapolis, a minister asked the crowd to pray for Dunham as a "source of comfort, healing and courage." Obama said his grandmother has been inundated with phone calls, e-mails and flowers from strangers.

"And so maybe she is getting a sense of, of long-deserved recognition at — towards the end of her life," Obama told ABC.

Obama was born in Hawai'i. His Kansas-born mother and Kenyan father met as college students there, but Dunham and her husband, Stanley, raised Obama for extended periods when his mother lived overseas.

In his memoir "Dreams from My Father," Obama described his grandfather as something of a dreamer. It was his grandmother who was practical enough to support the family by working her way up in the ranks at the Bank of Hawaii.

Obama has often mentioned "Toot" — his version of the Hawaiian word "tutu," or grandparent — as an example of a strong woman succeeding through intelligence and determination. Many of his speeches describe her working on a bomber assembly line during World War II.

"She's really been one of the cornerstones of my life. She's a remarkable woman," he said.

Obama planned to visit his grandmother last night and today and return to campaigning in Nevada tomorrow.