Paul Mirengoff, writing at Powerline:
[Democratic] debate centers around a resolution [that labels] the Iranian Revolutionary Guard Corps (IRGC) a terrorist organization. There's no genuine dispute that the IRGC fits this description, and none of the serious Democratic candidates denies it. Moreover, unlike the question of whether Turkey committed genocide 90 years ago, the status of the IRGC is relevant to today's world. Finally, unlike Turkey, Iran is an enemy of the U.S., not its ally.
Accordingly, Hillary Clinton voted for the resolution. That vote has produced harsh criticism from Barack Obama (even though he skipped the vote), John Edwards, Joe Biden, Chris Dodd, and Bill Richardson. They argue that the designation of the IRGC as terrorists could embolden Bush to take unilateral military action against Iran.
...Even so, it's difficult to blame Obama and the others from seizing upon Hillary's vote. The Democratic base is so stridently pacifist and so paranoid about Bush that even a non-issue like this one has the potential to generate heat. Clinton certainly sees this danger. According to the Post, she has "flooded Iowa with a mailer that included a lengthy letter from the candidate explaining why she supported [the IRGC] measure."
It's not easy being a semi-serious figure seeking the nomination of a frivolous party.