Fallows hits the nail on the head:
You could also argue, from a purely operational perspective, that as the first woman ever to have a plausible chance to become president, Hillary Clinton is the one candidate who can never ever appear to be "soft." It's fine for senators like Jim Webb or Chuck Hagel, with their Vietnam-combat photos on their office walls, to say that a particular war would be rash, unnecessary, doomed, or self-defeating. Indeed, both of those senators were among the 22 with the guts and sense to vote against Kyl-Lieberman. (Barack Obama said he was against the measure, but he didn't change his campaign schedule to show up and cast a No vote.) But -- the operational argument would continue -- the moment a Democratic female candidate cast such a vote, she would lose her "political viability within the system," in words her husband once used.
I can understand that logic. The question in: when does it end? If the experience of supporting the Iraq war wasn't enough to embolden her to oppose Kyl-Lieberman and its implied threat of war with Iran, what would? If she is sworn in as the first female president, she will still have to remove doubts about her "toughness." There will be the 2010 midterms to think of. And of course the 2012 reelection campaign. And if she is tough enough to get through that, then concerns about her legacy. Over the long run, is there any difference between a candidate who needs to "seem" hawkish on questions like Iraq and Iran, and a candidate who is an actual hawk?
Clinton's foreign policy is determined by the post-Reagan Democratic defensive crouch, compounded by the gender issue. It gives her much less flexibility as a potential president than Obama. On the key questions on Iran and Iraq, Clinton's judgment has been wrong and Obama's right. Doesn't all this have to make a difference? On the war, why on earth would a Democrat want to elect a punching bag who is already afraid of the VRWC?