HONOLULU -- Sen. Barack Obama's spokesman confirmed that the Democratic candidate for president will travel to Hawaii to visit his grandmother who is seriously ill.

Obama's spokesman Robert Gibbs told reporters on a flight from Orlando, Fla., to West Palm Beach to announce that on the senator will head to Hawaii Thursday afternoon.

Madelyn Dunham is seriously ill, Gibbs said. She was released from the hospital last week and is at home.

Her brother said on Tuesday she is "gravely ill."

"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," Gibbs said in a written statement.

"Recently, his Grandmother has become ill, and in the last few weeks, her health has deteriorated to the point where her situation is very serious. It is for that reason that Senator Obama has decided to change his schedule on Thursday and Friday so that he can see her and spend some time with her. He will be returning to the campaign trail on Saturday," Gibbs said in the statement.

The campaign canceled Obama's events in Madison, Wis., and Des Moines, Iowa. He will speak at an event in Indianapolis Thursday morning before leaving.

The spokesman would not say what kind of medical illness Dunham is suffering from.