"I'm wither her," Oprah Winfrey announced.

Media mogul Oprah Winfrey is supporting Hillary Clinton in the U.S. presidential election.

"I really believe that is going to happen," 62-year-old Winfrey told ET's Nancy O'Dell during the premiere of her new OWN drama, Greenleaf. Winfrey said that she believes that the time is ripe and "that we make that decision." She was referring to the election of the first female president of the United States. 

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Winfrey considers Clinton's nomination as a breakthrough moment for women.

"I would also say, that regardless of your politics, you cannot be a woman in the world and not see that this is a monumental time for women breaking the ceiling," she said during an interview on ABC, saying that Hillary's candidacy is "about breaking the ceiling!"

Winfrey also said that she is ready to do her fair share if needed in the campaign.

"If I felt like, yeah, I'm really needed out there, then yeah, I would do it," she said.

Winfrey is one of the high-profile personalities who have cried "I'm with her" (Clinton's slogan), joining President Barack Obama and First Lady Michelle Obama in openly support Clinton.

Winfrey was at the White House on Tuesday to attend the United States of Women Summit, where she and Michelle Obama talked about gender equality. The first lady also revealed how it is to live in the White House and the first family's plans and thoughts about life after the presidency.

In the 2008 elections, Winfrey threw her support behind Barack Obama, who emerged as the first Black American president.

Meanwhile, Winfrey is slated to launch a cookbook, Food, Health and Happiness: 'On Point' Recipes for Great Meals and a Better Life, and she spoke excitedly about it. She called the book her "food story," a story she is sharing after finally resolving her "long journey with food."

However, Winfrey told ET's Nancy O'Dell that she does not cook every day and that she has cooks who prepare her meals, saying the book is a product of "those chefs' ideas and my ideas."

Tagsoprah winfrey, Hillary Clinton, James Corden