Oprah Winfrey: Supporting Obama '100%'

Oprah Winfrey told CNN Friday that she is "100%" behind Barack Obama and she believes he's a "masterful leader."

The talk show host made her comments to the network during an interview in South Africa, where 72 students at the Oprah Winfrey Leadership Academy for Girls will graduate on Saturday.

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Winfrey was key in raising money and support for Obama four years ago. She indicated that this time around would be no different, if the president calls on her for help.

"If he or his office called me tomorrow and said that they needed me I would do whatever I thought would be of service," she told CNN. "I did what I did in 2008 because I really thought that would be of value and of service. I don't think that's needed in 2012. There's not a person in the world who doesn't know who Barack Obama is."

CNN asked Winfrey if she would be officially endorsing Obama. She said: "I don't need toendorse him because I am a 100% supporter of him and I've already endorsed him," she said.

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Winfrey said she believes "getting our economy back in order" will be Obama's biggest challenge if he's reelected.

"It's the same thing as the first four years, and that's getting jobs for people, and getting our economy back in order, and building a sense of confidence in the American people so that they know that their futures can be sustainable," she said.

She added that she's "proud" of Obama.

"I think he's a masterful leader," she said. "What it t! akes to be able to do that on a daily basis and to stand up in a world where everyone is just open to attacking you all the time -- it's a very hard job."