From W's 4/13 press conference:
Q Thank you, Mr. President. In the last campaign, you were asked a question about the biggest mistake you'd made in your life, and you used to like to joke that it was trading Sammy Sosa. You've looked back before 9/11 for what mistakes might have been made. After 9/11, what would your biggest mistake be, would you say, and what lessons have you learned from it?
THE PRESIDENT: I wish you would have given me this written question ahead of time, so I could plan for it. (Laughter.) John, I'm sure historians will look back and say, gosh, he could have done it better this way, or that way. You know, I just -- I'm sure something will pop into my head here in the midst of this press conference, with all the pressure of trying to come up with an answer, but it hadn't yet.
... I hope I -- I don't want to sound like I've made no mistakes. I'm confident I have. I just haven't -- you just put me under the spot here, and maybe I'm not as quick on my feet as I should be in coming up with one.
From Clinton's 6/24 appearance on Larry King:
KING: What was your biggest mistake in the office?
CLINTON: That's pretty hard. I think my biggest mistake as president as opposed to as a person -- we know what my biggest personal mistake was. But certainly one of the biggest mistakes I made was continuing to push in the first two years of my presidency to pass healthcare reform when it was obvious that the Republicans had made a decision that no healthcare reform would pass, or at least the leadership had. If instead I had done what my instincts should have told me to do and pass welfare reform first and then said after the election we'll try to get a bipartisan healthcare reform bill through, we might not have lost the Congress. And that might have been a good thing. You know, I think that was a significant mistake.
One of my great regrets in foreign policy is not sending troops to try to stop the Rwandan genocide when I realized how severe it was. It happened very fast, 90 days, 10 percent of the country, 700,000 people killed with machetes. I feel terrible that we didn't do it. We were still kind of reeling from Somalia and we were trying to get into both Bosnia and Haiti. So that the whole thing was never seriously considered. And when I finally came to grips with the magnitude of it -- I will always regret it.
------------------
"I will never apologize for the United States of America, ever. I don't care what the facts are."
G.H.W. Bush, 8/88 [I've seen small varitations on the quote above, and various dates]
Clinton - again, from Larry King:
CLINTON: Well I did on occasion. But I don't think -- you know, I've often wondered whether I should have even done it more than I did. But I did so on occasion.
And I apologized for the country, too, on occasion. You know when I went to Africa and said I was sorry for slavery and I went to Rwanda and said I wished that we had intervened and stopped the Rwanda genocide. And I felt terrible about it.
I was actually criticized sized by some in America saying you know the president should never go overseas and admit any error, whatever. Well it's -- we have a great country. And it's the greatest country in human history because it has been flexible enough to change and overcome error. You know we were wrong when we started this country and we only let white male property owners vote and we counted African-Americans as, you know...
KING: Three-quarters.
CLINTON: ... three-fifths of a human being. We were wrong. It's OK to say we were wrong.
KING: Would you therefore have apologized for the occurrences in the prison?
CLINTON: Oh, yes. Of course. Just like I call Jiang Zemin and apologized for bombing the Chinese embassy in Belgrade during the Kosovo War. Of course I would.