Arianna Huffington dishes it out as to why the Democrats lost this election:

But it wasn't gay marriage that did the Democrats in; it was the fatal decision to make the pursuit of undecided voters the overarching strategy of the Kerry campaign.

This meant that at every turn the campaign chose caution over boldness so as not to offend the undecideds who, as a group, long to be soothed and reassured rather than challenged and inspired.

[...]

With Iraq burning, WMD missing, jobs at Herbert Hoover-levels, flu shots nowhere to be found, gas prices through the roof, and Osama bin Laden back on the scene looking tanned, rested, and ready to rumble, this should have been a can't-lose election for the Democrats. Especially since they were more unified than ever before, had raised as much money as the Republicans, and were appealing to a country where 55 percent of voters believed we were headed in the wrong direction.

Direland dishes it out as to why they will lose the next election.

Undoubtedly, the Corporate Democrats and their liberal power-junkie helpmates will decide that they lost the election because they didn’t squirm far enough to the right. Where is the institutional leadership--or the leader--who could fight for a reorientation of the party toward a populist, progressive, passionate commitment to social and economic justice as a REAL alternative to reactionary Republicanism? Oh, Hillary Clinton, you say? Don’t make me laugh. But she’ll undoubtedly be the Democrats’ nominee in 2008--which is why we can expect, not four more years of Republican rule, but 12.