Dr. Mehmet Oz is the GOP nominee for Pennsylvania senator this election, but his campaign was dealt an embarrassing blow when former mentor Oprah Winfrey publicly voiced her support for his opponent, John Fetterman. While hosting “A Virtual Voting Conversation” on Thursday, November 3, the media mogul announced her endorsement of Fetterman, along with several other candidates including Beto O’Rourke for Texas Governor, Stacey Abrams for Georgia Governor and Raphael Warnock for Georgia Senator. “I said it was up to the citizens of Pennsylvania and of course, but I will tell you all this, if I l…