In discussing a replacement for President Barack Obama with his then-chief of staff John Harris, Blagojevich said Winfrey's "up there so high, no one can assail this pick." Blagojevich was casting about for a nominee who could afford him the most benefit after Obama friend Valerie Jarrett took her name out of the running, the Chicago Tribune reported.
Blagojevich is on trial for allegedly trying to parlay his official duties for personal benefit and campaign contributions. He is accused of attempting to sell Obama's seat to the highest bidder.
The testimony came as Harris underwent questioning.
U.S. District Judge James Zagel denied a request by the defense for FBI notes of interviews with Obama.
"There's nothing remotely relevant to this witness's testimony," Zagel said.