Surprise, the motivation for it is political! (very cynical politics, imo)
Bush is very against it for obvious reasons, but since it is only a non-binding congressional resolution, it doesn't need his signature and he can't veto it. He has no control over it.
See:
http://www.humanevents.com/article.php?id=22840#
and WSJ op-ed's take:
http://opinionjournal.com/editorial/...l?id=110010738