Joseph Lieberman has always been and has always voted exactly like who he is. Whether you have agreed with his votes or not (and to be sure, I have disagreed with many of his votes) you cannot say about him that he has pandered or compromised his beliefs. It is not as if he campaigned one way, then turned around and became a completely different senator then the one that the Connecticut voters elected. Knowing him and his belief system, you can usually predict how he will vote on an issue. Lieberman is a Modern Orthodox Jew (those unfamiliar with this brand of Judaism should check this Wikipedia entry http://en.wikipedia.org/wiki/modern_orthodox_judaism ). People familiar with my articles know that I am Jewish as well, but more on the reformed side, but I am very familiar with the branches of Judaism and their beliefs. In general, Jews are overwhelmingly Democrats, but those who are more observant and tend towards religious orthodoxy tend towards political conservatism. Put more succinctly, most Orthodox Jews are Republicans. While I cannot quantify what I am about to say from any empirical sense, I believe that of the various sects of Orthodox Jews, only the Modern Orthodox have a large amount of Democrats in their ranks. Knowing what Modern Orthodoxy is this is not surprising. Modern Orthodoxy attempts to reconcile the biblical laws with the secular world achieving the best possible harmony with both. However, where there are significant conflicts, the Modern Orthodox Jew will select biblical over secular. A good example of this with Lieberman along with an example of a conflict between Modern Orthodoxy and other sects of Orthodox Judaism can be seen in this article http://www.cnsnews.com/viewpolitics.asp?try=no&page=\politics\archive\200008\pol20000814k.html, where a traditional Orthodox rabbi lambastes Lieberman for some of his views while a Modern Orthodox rabbi defends him.
There are many dangers in Progressive Democrats intentionally trying to run Lieberman out of his senate seat. For one, those who support the ouster of Lieberman are saying the Modern Orthodox Jewish beliefs have no place in the Democratic Party. It is putting a line in the sand and saying that if your beliefs are past this certain point you cannot be a Democrat. What we should be doing is to put forth a consistent set of values that typify the Democratic Party belief system, educating the public about why this belief system is best, and trying to influence all of our candidates and elected officials to adopt these values. Each branch of the Democratic Party should do this and fight for their particular views in the overall party platform. Progressives should understand that large segments of the country do not agree with them on the issues. It is much more important and effective to deal with this by using dialogue and education. Kicking people out of the party and such is not an effective means to accomplish the ultimate goal of a progressive country. It is an effective way of alienating people and shoring up the opposition and presenting the Democratic Party as out of touch with more and more people. The Republican Party already uses the line "The Democrats are out of touch with most Americans" frequently in their interviews and stump speeches. Shrinking the tent by kicking people out at the fringes only will reinforce this viewpoint.
I believe that having Senator Joe Lieberman in the party and in the Senate as a Democrat is a big plus for the Democratic Party. It shows our strength and the bigness' of our big tent. We still should articulate our displeasure to him for various votes or stances with which we may not agree but attempting to run him out of the senate is not the answer.