"A lot was made of the fact that Al Gore abandoned his former running mate, Joe Lieberman, when he decided to endorse Howard Dean for the Democratic presidential nomination.
Traditionally, political etiquette demands that, if a member of a national ticket in one presidential race is seeking the presidency four years later, the other member of the ticket should not turn around and urge voters to back someone else. This is especially true when, as was the case with Gore, the candidate you chose to join you on the ticket is now running in his own right.
But no one should fret for Joe Lieberman. Indeed, it is reasonable to argue that Al Gore is not president today because of Lieberman.
...
Al Gore did not let Joe Lieberman down when he endorsed Howard Dean. It is Lieberman who has let Democrats down, again and again. His loyalties lie with the corporate-sponsored Democratic Leadership Council, not with the grass-roots Democrats who remain furious about the dubious manner in which George W. Bush obtained the presidency and about the even more dubious manner in which he has exercised the powers of that office.
..."
http://www.madison.com/captimes/opinion/column/nichols/63055.php