Billionaire philanthropist Oprah Winfrey is set to take the stage at the Democratic National Committee in Chicago, for a surprise speech in support of Vice President Kamala Harris’ 2024 campaign. Winfrey has a history of political involvement with Presidents Barack Obama and Joe Biden. She is expected to speak enthusiastically in favor of the Harris-Walz ticket. Winfrey’s appearance was announced last-minute. She joins a jam-packed lineup Wednesday that also includes speeches from former President Bill Clinton and the vice presidential running mate himself, Minnesota Gov. Tim Walz. Want more b…