George W. Bush leaves office with a job-approval rating that once soared to historic highs, then fell slowly but steadily for five years before settling, in the last couple of years, into lows that no president has ever experienced for so long. The president’s final Gallup approval rating of 2008 is 28 percent; a number like that means some core Republicans don’t approve of Bush’s performance, and even among the many in the GOP who still approve, there are a number who are ready to see the president go. Bush knows that. The White House staff knows it. But the...