Kleefeld continues: "Lieberman's overall approval rating is only 25%, with 67% disapproval. Democrats disapprove of him by 14%-81%, Republicans by 39%-48%, and independents by 32%-61%. Only 19% approve of his actions on the health care bill, with Democrats at 8%-80%, Republicans at 26%-55%, and independents at 30%-59%. Among those who support the bill, 84% disapprove of his handling of the issue, and in addition 52% of the people who don't support the bill also disapprove of Lieberman's actions."
I think you have to set aside the gravity of the health care situation in America a little bit to get a clear picture of how bizarre Lieberman's behavior has been. Otherwise you just see him as a really bad guy, which he is, but you get so infuriated that it's hard to fully appreciate the extent to which his actions don't seem to make any internal sense, even for a bad guy. The best I can think of is that he lost his ability to consider any political strategies beyond "annoy both parties and elite centrists in the media will love you, leading to all sorts of goodies."