The previous sentences are obvious, nevertheless they are apparently "politically incorrect" at many corners of the "Democratic Party".
The New York Times inform that a group led by James Dean, the brother of the DNC chairman Howard Dean, has collected 30,000 signatures of confused people and they will send the critical letter to Joe Lieberman. The obnoxious communist movement moveon.org claims that they will try to replace the popular senator of Connecticut at the polls - which, of course, does not sound terribly realistic. At any rate, I would call these things intimidation.
This intimidation is not only wrong. It also shows a deep misunderstanding of the political facts. Joe Lieberman was, together with John McCain, a co-author of a bill that has made overthrow of Saddam Hussain an official U.S. policy in 1998. I wonder why do the "Democrats" exactly think that Lieberman would suddenly start to follow their "official" dumb anti-war ideology whose only purpose is to create new problems for George W. Bush and for all of us. In reality, Lieberman has historically been more connected with the hawkish attitude towards Hussain's regime than George W. Bush himself.
More generally, it is also nonsense to argue that the tradition of the Democratic Party would justify an official anti-war stance of all members. It was the Democratic Party administrations that have involved the U.S. in virtually all big wars of the 20th century. The First World War, the Second World War, Vietnam, and Kosovo are examples. Clinton also started the Desert Fox in 1998, being convinced that Iraq had WMDs. Almost everyone whose opinion mattered was convinced it was the case. Madlenka Albright was as hawkish as Donald Rumsfeld; see for example this page. The Bush administration simply inherited a system of policies and opinions and acted in this framework.
Lieberman would be one of the most natural Democratic candidates for President in 2008 but I am afraid that there are too many loud, far left-wing lunatics within his party who will make it impossible.