Re:I think Truman said it... (Score 0)

Well, not necessarily. Draw a line representing the spectrum from Democrat to Republican. (Yes, it's more complicated than a line, but I'm being not unreasonably simplistic for the purposes of this example.) Now mark the line where you think Bush stands. You are running against Bush in the next election. People will vote for whichever mark is closer to their position on the line. Where do you place your mark to get the most votes?

There is a danger that if you're too close to Bush's mark, the Democrats sufficiently far from you might split and do one of those third-party "we're not going to win, but our candidate brings our views to the table" things. However, if we ignore that possibility, you place your mark to the left of Bush but as close to him as possible. And even with that possibility, you place your mark as close to Bush as you can get under the constraints of the risk of third-party split.