From WNYC in New York, this is NPR's On the Media.

I'm Brooke Gladstone.

And I'm Bob Garfield.

This week, a famous TV personality entered the political arena.

No, not Fred Thompson, who did finally throw his hat into the ring.

I'm talking about Oprah.

He is someone new.

Someone, I think the country, needs to get to know.

This is my senator, my favorite senator.

I really do believe in Barack Obama.

If he was running for mayor, you know, school superintendent, if he was running for president,

I believe in him.

Oprah Winfrey appeals to an impressive base of potential voters.

Nearly 8.5 million people watch her program every weekday, 2 million, by her magazine.

And those are just two components of a media empire that has made her, according to Forbes,

the wealthiest woman in the entertainment industry.

Until this presidential race, Winfrey has never publicly endorsed a political candidate.

But this weekend, she's hosting a $2,300 a plate fundraiser at her California home for Barack Obama.

The celebrity endorsement is certainly nothing new in presidential politics.

But as University of Southern

California history, Professor Steve Ross explains, Oprah is no regular celebrity. Oprah's endorsement

is probably the most important celebrity endorsement in the worlds of television and film that

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