Dick Morris has some insight into the structural problems facing the modern Democratic party; most of his observations are commonly known, except for one I hadn't considered before:
Their [the far-left Democrats] ascendancy is paralleled by the solidification of the Democratic minority in Congress, cemented in place by the 2001 reapportionment in which GOP leaders drew district lines to concentrate Democrats in Democratic districts and keep Republicans and independents in marginal areas.I can see how redistricting could lead to a minority party electing more extreme candidates, as majority and independent voters are siphoned into seperate districts. Since Congressional reapportionment only takes place once every ten years, the Democrats will face tough primaries that will empower far-left candidates for quite a while, even if Howard Dean loses ignominiously in 2004.
The result has been an inoculation of Democratic congressmen against defeat in general elections. But, with huge numbers of Democrats in their districts, they do have to fear primary contests, particularly on the left. This realization impelled the election of California’s Nancy Pelosi as minority leader and marks the House Democrats’ move to the left and to irrelevancy.