John Quiggin points to a post by Stephen Kirchner in which Kirchner alleges that Quiggin wouldn't be so upset about the projected US budget defecits if the president causing them were a Democrat. This sort of thing -- "you wouldn't say that if it were the other party proposing it" -- is one of my least favorite rhetorical strategies. It takes the focus away from the actual issue, and it's usually nearly impossible to prove one way or the other. There are, however, two situations in which this type of argument is valid: 1) the person's argument is explicitly based on their feelings for the person proposing the policy ("I support the war because I trust President Bush to do the right thing") or 2) you can cite an actual example of the person taking a different stance in a similar situation under a different administration ("You supported Clinton's attack on Serbia, which is no different from the situation with Iraq"). Note that in number 2 the person may validly counter by saying either that there is some important difference between the two situations, or that they were mistaken in the earlier situation.