On Feb. 21, Doubleday will publish the book that cost me my job: "Impostor: How George W. Bush Bankrupted America and Betrayed the Reagan Legacy." The germination began when I heard about the extraordinary efforts made by the White House to ram the Medicare drug benefit through the House of Representatives during the night. Until that point, I had given President Bush the benefit of the doubt—even on things with which I was uncomfortable. For example, I had reluctantly concluded the Iraq War was justified on the basis of what I knew at the time it began. I don't normally...