The Left believes that they are so much better in solving the lives challenges that they must have Power no matter what. The goal justifies the means. Not that they really "want" the defeat. Its just on the balance of things its irrelevant comparing to them getting the Power back.
That's why they put themselves into a position of contradicting decades of their criticism of, for example, a "realist" politics of supporting "our SOBs". Now, when the administration tries to promote a freer and more liberal society instead of just installing another dictator, they are against it. Somehow they don't care that their actions are effectively aligning them with forces hostile to human rights, women rights, gay rights, artistical expression and any expression of personal liberty.
A recent response of a majority whip that a report of a success of the surge will be a "problem" is amazing in its honesty. I'd presume that one would be ashamed to admit that narrow partisan interests are higher than national. At least, one would expect more weaseling "wisdom" from a party muckety-muck (a whip is not just a no-name congressman!). But looks like they just don't care. Not that conservatives and republicans are exempt from partisan exaggerations, but it is multitudes smaller. The current Leftist power-grab drive cynicism is on the level of Bolsheviks'.