The 2004 Presidential campaign put Democrats at a marked disadvantage: running against a popular incumbent, in a time of "war." One component of that disadvantage is that the incumbent doesn't have to win Primaries; in fact, the incumbent's message gets out unfiltered.
On the other hand, as the opposition party, the Democrats had the polar opposite: 10 candidates, all with different viewpoints on the country and the future, all vying to relay their message as it relates to all the issues facing our country.
Because there will be no incumbent and no Vice President running for the opening, 2008 threatens to mirror 2004 on both sides: a free-for-all in which numerous candidates in both parties vie for their respective parties' nomination.
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NOW is when the Democrats can exercise a tactical advantage: it's time for Howard Dean, or someone else behind the scenes, to twist some arms and convince those who do NOT have a legitimate shot at the nomination to NOT RUN.
I'm sure this will sound unpopular, but let's think for a moment: if there are 4 Democrats in a 2 hour debate, each gets roughly 30 minutes to clarify a position; with 10, each only gets 12 minutes. If we run fewer candidates than the other party, our candidates have a time advantage in the Debate process.
"Who shouldn't run?" is the difficult question. Though as a freedom-loving American I hate to suggest anyone should not run, it would be to the party's advantage to quiet those who, realistically, do not have a chance at the nomination. In 2004, three candidates who had no real chance were at the debates: Kuchinich, Brown and Sharpton.
As much as I like SOME of Kuchinich's positions--and I deeply admire his bravery for taking unpopular positions and sticking to them--intellectually I recognized he had absolutlely no shot in hell of the nomination, and even less at beating George Bush. The presence of three pretenders took valuable debate time away from the legitimate candidates with a chance; in some sense, that valuable time in the national spotlight might've either (a) pushed Kerry over the top, or (b) given the electorate a bit more information with which to make a better choice.
I'm not here to argue who should have won in 2004, or who should win in 2008. All I'm saying is that the ones who realistically can't win should STAY HOME to help us win the election.