In an interview for NBC, David Gregory asks George W. Bush if all the candidates' talk of "change" shouldn't be interpreted as a repudiation of his presidency. The president says no. "If I were running for office at this point, I'd be saying, 'Vote for me. I'm gonna be an agent for change.'"

Bush said that it's just the nature of American politics -- "You can't run for office and not say, 'I am an agent of change.'"

That's probably true when the president-to-be-replaced has approval ratings hovering around the freezing mark. But when the incumbent president is popular -- when the incumbent president is, say, Ronald Reagan, and the man trying to replace him is, say, George H.W. Bush -- it's not so necessary to declare oneself an "agent of change."

Or as that Bush put it during the 1988 Republican National Convention: "Now, after two great terms, a switch will be made. But when you have to change horses in midstream, doesn't it make sense to switch to one who's going the same way"?