[Now updated for clarity and symbolic reasons!]
I can see from the comments on John’s post below that there is some confusion out there about the way the American political system works. Specifically, there seems to be some serious misunderstanding of the dynamics of national elections in the US. So let me try to clear this up once and for all.
You are welcome.
Basically, post-Watergate America works like this. It’s what you might call a “twelve-step” program.
1. Democratic president is elected after disastrous Republican administration messes things up bad. Liberals rejoice, hoping that their long national nightmare is now over.
2. Democratic president turns out to be liberal–centrist fellow with some degree of cultural conservatism and willingness to echo Republican talking points on a handful of issues.
3. Democratic president meets with solid Republican opposition in Congress as well as various forms of obstructionism from members of his own party.
4. Democratic president gives in to Republicans repeatedly on a handful of symbolic (and therefore important to politically active voters) issues, appointments, regulations, etc.
5. Left wing of Democratic party erupts in outrage at sellout Judas stealth-Republican president.
6. Portion of left wing of Democratic party leaves party, goes home, fantasizes about awesome third party that will destroy the system and rebuild it from scratch.
7. Democratic president faces (a) stunning losses for his party in midterm Congressional elections or (b) primary challenger who divides the party and weakens the incumbent in the general election.
[Update: Goodness gracious! Now I see what all the fuss is about in comments. People are assuming that I think (7) is caused exclusively by (6). But that is so silly! As some of you have been kind enough to point out, there are many other factors at work behind (7), ranging from the state of the economy to the fired-upedness of Republican voters determined to punish the potsmoking/ philandering/ socialist/ Kenyan/ Muslim Democratic president for being president. Really, the whole point of the post was simply that Obama is hardly the first Democratic president to alienate the left wing of his base. On the contrary, it is required by the secret twenty-second-and-a-halfth amendment to the Constitution, ratified on November 1, 1960!
Sorry for the confusion, folks!]
8. Democratic president is up for re-election, or his vice-president seeks the office after president completes two terms. Disappointed liberal and left intellectuals convince themselves that Republican challenger can’t be all that much worse than Democratic candidate, since Democrat is sellout Judas stealth-Republican to begin with, Republican candidate will surely be more moderate than he appears when he is pandering to his base, and both candidates are working within the very narrow parameters of the corporate duopoly anyway.
9. Republican president takes office and makes things far worse than disappointed liberal and left intellectuals could possibly have imagined, lurching far to the right, empowering elements of his own party that were once considered “fringe,” and sweeping along one-third to one-half of the Democratic party as well. It turns out he wasn’t just pandering to the base after all! Who could have known?
10. Republican president wipes out previous Democratic president’s modest gains and accomplishments, which are belatedly acknowledged and viewed in nostalgic retrospect by Democratic voters appalled by Republican president, and seeds every tier of the judiciary with radicals whose decisions will hobble next Democratic president’s sporadic attempts to strengthen the social welfare state.
11. Democratic president is elected after disastrous Republican administration messes things up bad. Liberals rejoice, hoping that their long national nightmare is now over.
12. See step 2. Move three steps to the right and lather, rinse, repeat.
 Just for the record, this would be me in 1979 and again in 1995. RIP, Citizens Party and New Party. We had joy, we had fun, we had seasons in the sun.
 This would be me in 1980 but not in 2000. Fool me once, can’t get fooled again.