Americans for multilateralism
This poll finds that Most Americans Favor Action Against Iraq, but only 20 per cent support unilateral action without support from Western allies. I am encouraged by this evidence of support for multilateralism, which is usually drowned out by the noise generated by the warblogger right and the old-style leftists who are always opposed to any kind of military action. An operation to remove Saddam, based on UN resolutions, and with a commitment to the long-haul work of restoring democracy (the strong point of the European allies) would be justifiable in my view, whereas a Bush-Saddam vendetta is not.
Of course, to secure the resolutions, the US would need to prove that Saddam is still producing weapons of mass destruction, give him appropriate ultimatums and so forth.
Update:James Rubin sets out a lot of the same arguments here