The discussion continues this afternoon over what critics say is a possible conflict of interest for PBS' Gwen Ifill, related to her yet-to-be released book, "The Breakthrough: Politics and Race in the Age of Obama", and her moderating duties tomorrow night at the VP debate.

News of the book has "been out there and discussed for months," NewsHour spokesperson Anne Bell tells TVNewser. "We stand by Gwen's journalistic integrity."

Ifill had spoken about "Breakthrough" in a Washington Post interview last month, and it is mentioned in her official PBS/Washington Week bio.

Sen. John McCain commented on the story today, telling FNC's Carl Cameron, "I think that Gwen Ifill is a professional, and I think she will do a totally objective job because she is a highly-respected professional. Does this help that if she has written a book that's favorable to Senator Obama? Probably not. But I have confidence that Gwen Ifill will do a professional job." The McCain campaign has said it was previously unaware of Ifill's book.

Ifill's PBS colleague Judy Woodruff is also speaking out today, telling the Huffington Post that Ifill will show no bias. "Of virtually all the reporters I know," Woodruff says, "Gwen is somebody I have no idea where she stands politically. I mean, I have no idea where she is."