While the conduct of Dem leaders in the Geneva Conventions debacle has been pathetic, it would be a huge mistake to pretend that this election doesn't matter, that Dems are just as bad as Republicans, or that things are so screwed up that nothing matters anymore.
For starters: Republicans want to stay in Iraq, bomb Iran, suppress the basic oversight function required to be served by Congress in the American system of government, transform America into a police state (and yes, it could get much, much worse than it is now), cement America's post-9/11 adversarial relationship to most of the world, weaken the UN, dismantle social security, further stack the federal judiciary (not just the Supreme Court) with lunatics, further erode the separation of Church and State, amend the Constitution to entrench discrimination against homosexual Americans and roll back already insufficient environmental protections just as it becomes clear that the global warming crisis is far more severe than most of us had realized. It's so painful to watch Dem leaders blow it precisely because the stakes are so high.
In 2000, lots of people supported Nader on the theory that there was no meaningful difference between Gore and Bush. That's looking like a pretty dumb call right now, isn't it? Wouldn't punishing the Dems for their incompetence by staying home on election day be even dumber, now that everybody has the benefit of hindsight?
UPDATE: Edited to change "function ... played" to "function ... served".