Opponents have used Obama's name and his Kenyan father's ethnicity to portray the Democrat as an outsider. A series of Internet rumors inferred that Obama is a Muslim and Arab. He is neither.
"Obama has a very compelling family story, and any opportunity to remind people of that helps," said Clarke. "Attention on his grandmother neutralizes and lessens questions that he is an outsider with a strange, unknowable family."
Obama has spoken about his grandparents on the trail. While his grandfather fought in Patton's army in World War II, his grandmother worked assembling airplanes, a real life "Rosie the Riveter."
"My grandmother worked on a bomber assembly line, and my mother was born at Fort Leavenworth. After my grandfather stood up for his country, America stood by him. He went to college on the GI Bill. He bought his first home with help from FHA [Federal Housing Authority], and moved his family west to Hawaii, where he and my grandmother helped raise me," he said at a rally in June.
Later she would "work her way up from a secretary at a bank to become one of the first women bank vice presidents in the state," Obama said.
Obama, along with his wife, Michelle, and daughters, Malia and Sasha, last saw Dunham in Hawaii in August, with daily visits confined to her apartment because Dunham was too frail.
Obama, then acutely aware of her health, suggested that it was important for his children to spend time with their great-grandmother given her advanced years.
"I'm going to see my grandma who I haven't seen in almost 18-19 months," he said the day before the family took off for its vacation. "And, you know, who's getting to the age where I want to make sure that I'm spending time with her on a consistent basis and so that she could see her great-grandchildren. "
In April, Obama said Dunham was suffering from osteoporosis and was going blind, but Dunham's condition seems to have worsened, and he made his decision to visit after speaking with his half sister Maya Soetoro-Ng Sunday.
Dunham was reportedly hospitalized after a fall and "things have taken a serious turn," U.S. Rep. Neil Abercrombie, D-Hawaii, told the Honolulu Advertiser. "It's an accumulation of several difficulties. She's faced a lot of challenges," he told the paper.
Smith, the presidential historian, said Obama's willingness to hurry to Hawaii for his grandmother could help him with undecided voters.
"If you're an undecided voter because you just don't quite know this guy -- you're not against him, but you don't have a gut instinct about him -- you might just be impressed by the fact that he would be willing to take a moment from the pursuit of ambition to do something everyone can understand and everyone can relate to," Smith told ABCNews.com.
"It suggests that there are things more important than winning an election. You can't communicate that aspect of your character in a campaign commercial," he said.
Senior campaign adviser Robert Gibbs told "Good Morning America" today that Obama's strategists know the detour "comes at a cost on the campaign trail, but Sen. Obama believes his family comes first.