Winfrey has raised $3 million for Democratic presidential hopeful Barack Obama and may campaign for the senator from Illinois, but that doesn't guarantee she'll win him many votes, USA Today reported Monday.

A USA Today/Gallup Poll indicates more than six in 10 adults say endorsements aren't important in deciding whom they'll back. Only 8 percent of the adults interviewed for the poll taken Oct. 12-14 said Winfrey's endorsement of Obama made them more likely to vote for him, while 10 percent said it made them less likely to back him.

"There are some things that people will take their cues from (celebrities) and other things they won't," said Andy Kohut, director of the Pew Center for the People and the Press.

"If Bill Gates suggested something to me about technology or the future of the American economy, yes, very interesting," Kohut said. "But a choice between Mitt Romney and Rudy Giuliani? I'm not so sure."

The poll queried more than 500 U.S. adults, not all of them registered voters. No margin of error was given.