Two distinguishing features of American democracy: it is Madisonian, and it is situated in an enormously large nation. Take those together, throw in some individualism and with it the expectation that democracy means getting what you want, and you get a whole lot of frustration.
I've called this democratic frustration, and identified two major types. The first is what happens when you get involved, organize, work hard, and then lose. It can happen in any democracy, but it's especially difficult in a very large democracy, because it's impossible to have any sense of majority or minority out of personal experience. Indeed, given both geographic distribution of partisanship and the nature of campaigns, odds are that one's personal experience is going to be misleading. It sure seems, as Pauline Kael didn't really say, that everyone we knows agrees with us -- so how could our side lose? The classic manifestation of this type of frustration is the conspiracy theory, from Diebold to birtherism or Acorn: the other side didn't really win, after all.
The other type of democratic frustration is the one liberals have been experiencing over the last eighteen months: we won, so why aren't we getting our way? Again, it's a product of a very large nation and Madisonian democracy. The latter makes it very hard to do anything; the former means that when "we" won the "we" turns out to include lots of people who disagree on all sorts of things. This type of frustration yields the charges of sell-out and double-cross: from "let Reagan be Reagan" to Jame Hamsher's campaign against health care reform and Glenn Greenwald's various bits of mishegoss.
All of which is just a long-winded and self-serving way (I've been pushing this idea for a while) to introduce a link to a thoughtful article by Michael Tomasky counseling liberals to avoid self-destructive consequences of democratic frustration. It's a long essay, and I could spend plenty of time arguing with him on the details, but I think the big picture is exactly right. It's worth reading for everyone, but it's especially worthwhile if you like Obama, and like Chuck Schumer and Nancy Pelosi, and like the pundits and analysts who mostly support those pols and seem to spend a lot of time explaining why it's not always their fault when things go wrong (from a liberal point of view) -- but you also read critiques that accuse all those people of being insincere sellouts, and you find that interpretation tempting. What I can tell you is that's just the democratic frustration talking; what Tomasky can tell you is that it's always like that, even during the New Deal, and even during the Great Society.
Of course, knowing that democratic frustration is par for the course doesn't necessarily make it any less frustrating. It's important for activists, as Tomasky says, to keep the pressure on -- one of the key points to understand about a Madisonian system is that elections are only one part of self-government, and having the best shot at getting what you want requires engaging in politics even when there's no election on the horizon. And of course giving up the fantasy that all defeats are the deliberate choices of double-dealing pols doesn't mean that pols, no matter how sincere, won't make mistakes. Nor does it mean that pols will ignore electoral incentives, and so it's important to make sure (to the extent possible) that those incentives run the way you want them to.