This part here is really the key:

Taking a quick and admittedly crude look at the aftermath of our previous three landslide elections, I see a pattern where, once Democrats win, they naively assumed that the natural order of American politics has been restored and failed to act in ways that allowed them to maintain or expand upon their majorities. After 1964, Democrats governed quite poorly when it came to Vietnam, thereby dividing both the nation and their own coalition, and thus leading to defeat in 1968. After 1974, when Democrats took Depression-era leads in Congress, Jimmy Carter ran an extremely milquetoast, fluffy and image-based campaign once he sowed up the nomination. As we rested on our laurels, the conservative movement continued to dig in, and by 1978-1980, whatever gains we made were more than wiped way. In 1992, we won the trifecta back after twelve years, and then proceeded to run against tour own party once we had it. And so the 1994 landslide happened.

I was writing about the best case.  Worst case is that a wave one way is followed by a stronger wave the other way--which is the subject here.  What we need to do is put the two pictures together, side-by-side and ask, what makes one happen versus the other.  I agree with the general description that Chris laid out, but it's useful to make that description more exact.  Why did Democrats let Vietnam slide?  Well, it so happens that there's only one book, so far as I know, that deals with the role of Congress in the Vietnam War. A Grand Delusion: America's Descent Into Vietnam by Robert Mann.  The House doesn't really figure in it.  For historical as well as insitutional reasons, it was all about the Senate.   Publishers Weekly:

Mann, a former Senate aide, puts Senate-president politics at the center of this masterful political history of America's involvement in Vietnam, which began with Truman's commitment to support the French in the wake of charges of "losing" China to the Communists. Many of the senators who attacked the Truman administration were isolationists who voted against the realistic anti-Communist institutions such as NATO and the Marshall Plan. Yet such contradictions mattered little, as the Democrats' disastrous political defeat in 1950 and 1952 convinced them to never let another "loss" be blamed on them. The twin strands of ideological surrealism and political realism interweave throughout Mann's account in various forms, illuminating the persistent patterns and underlying motivational logic of presidential lies and congressional acquiescence. Eisenhower promised to end Truman's containment policy, but he delivered the Korean armistice and refused to fight in Vietnam. Two major congressional resolutions authorizing use of force led to the Gulf of Tonkin Resolution. Johnson promised "no wider war" while escalating for fear of "losing" Vietnam. Mike Mansfield - the Senate's foremost Asia authority, as well as majority leader - opposed America's deepening involvement, but his concept of his institutional role made him publicly loyal to Johnson's policies, which in private he strove mightily to change. Each participant responded distinctively to fundamental contradictions, brilliantly elucidated by Mann's highly nuanced account of presidential policy and the tortured evolution of Senate opposition. This book's unique perspective in illuminating Congress's role in the Vietnam War should permanently alter and deepen our understanding of that conflict.

The other two elections were, IMHO, much more about the Dems persuing the chimera of political reconciliation and bipartisanship with people who are uncompromising partisans who routinely put party above all else.  Clinton, in particular, turned his back on an unbelievable record of GOP malfeasance (with a small, but crucially positioned amount of Democratic involvement) and said, in effect, "We're not going to get into that.  We want to move forward together."  Well, we saw what that got us.

I'm not offering this as a definitive description.  It's just a comment, after all.  I'm stating it as a invitation for us to flesh this out more fully, because the lessons here are obviously of utmost importance.

We in the blogosphere are the only politically potent repository of historical memory.  (Obviously, there are folks who know the history much better than we.  They're called history departments.  But they aren't political potent.) The rest of the political system is so drenched in spin it wouldn't know real history if it walked up and bit them in the ass.  So it's up to us to take that history, ponder the lessons, debate their significance amongst ourselves, and then start getting the conclusions out into the wider world.

The natural, over-determined tendency of the Versailles establishment is to think in terms of cliches, myths, the CW and short-term time horizons.  These all lead to exactly the wrong sort of strategy, and one more repetition of the pattern Chris is writing about.

We can do better.

We have to do better.