Renewing the call for an independent investigation of classified national security disclosures that have been made public in recent media reports, 31 Republican senators sent a letter to U.S. Attorney General Eric Holder Tuesday, laying out the seriousness of the leaked information and the importance of an impartial probe.

For the first time, the senators also named names, citing a New York Times review of its own reporter David Sanger’s news-breaking book “Confront and Conceal,” which taps National Security Adviser Tom Donilon as a potential key source of the classified information.

“Mr. Donilon, in effect, is the hero of the book, as well as the commenter of record on events,” NYT writer Tom Ricks writes, in a quote that was reproduced in the letter.

But when Human Events asked Sen. John McCain (R-Ariz.) about Donilon at a morning press conference, the Arizona senator appeared to back down somewhat.