In the long lead up to Mrs. Clinton’s campaign announcement, aides proved adept in swatting down critical books as conservative propaganda, including Edward Klein’s “Blood Feud,” about tensions between the Clintons and the Obamas, and Daniel Halper’s “Clinton Inc.: The Audacious Rebuilding of a Political Machine.”

But “Clinton Cash” is potentially more unsettling, both because of its focused reporting and because major news organizations including the Times, The Washington Post and Fox News have exclusive agreements with the author to pursue the story lines found in the book.