Oprah Winfrey came out in support of U.S. presidential hopeful Barack Obama on Thursday - and burst into tears when the Democrat accepted his nomination.

The legendary chat show host, who has urged her viewers to vote for the Illinois senator, turned up at the Democratic National Convention in Denver, Colorado to back the politician.

And Winfrey said she was moved to tears by Barack Obama's acceptance speech.

She says, "I cried my eyelashes off. I think it's the most powerful thing I have ever experienced."

Obama accepted the nomination for presidency in front of 84,000 people on the 45th anniversary of Martin Luther King Jr.'s famous 'I have a dream' speech.

Winfrey adds, "He's not an African-American candidate. He's a candidate for Americans.”