How serious is the "thumpin'" the Republicans took on Tuesday? Losing one house is significant but hardly historic. Losing both houses, however, is defeat of a different order of magnitude, the equivalent in a parliamentary system of a vote of no confidence.

On Tuesday, Democrats took control of the House and the Senate. As of this writing, they won 29 House seats (with a handful still in the balance), slightly below the post-1930 average for the six-year itch in a two-term presidency. They took the Senate by the thinnest of margins -- a one-vote majority, delivered to them by a margin of 7,188 votes in Virginia and 2,847 in Montana.

Because both houses have gone Democratic, the election is correctly seen as an expression of no confidence in the central issue of the campaign: Iraq. It was not so much the war itself as the perceived administration policy of "stay the course," which implied endless intervention with no victory in sight. The president got the message. Hence the summary resignation of the designated fall guy, Secretary of Defense Donald Rumsfeld.

Nonetheless, the difference between taking one house versus both -- and thus between normal six-year incumbent party losses and a major earthquake that shakes the presidency -- was razor thin in this election. A switch of just 1,424 votes in Montana would have kept the Senate Republican.

A margin this close should no longer surprise us. For this entire decade the country has been evenly divided politically. The Republicans had control but by very small majorities. In 2000, the presidential election was settled by a ridiculously small margin. And the Senate ended up deadlocked 50-50. All the changes since then have been minor. Until now.

But the great Democratic wave of 2006 is nothing remotely like the great structural change some are trumpeting. It was an event-driven election that produced the shift of power one would expect when a finely balanced electorate swings mildly one way or the other.

This is not realignment. As has been the case for decades, American politics continues to be fought between the 40-yard lines. The Europeans fight goal line to goal line, from socialist left to the ultranationalist right. On the American political spectrum, these extremes are negligible. American elections are fought on much narrower ideological grounds. In this election, the Democrats carried the ball from their own 45-yard line to the Republican 45-yard line.

The fact that the Democrats crossed midfield does not make this election a great anti-conservative swing. Republican losses included a massacre of moderate Republicans in the Northeast and Midwest. And Democratic gains included the addition of many conservative Democrats, brilliantly recruited by Rep. Rahm Emanuel with classic Clintonian triangulation. Hence Heath Shuler of North Carolina, anti-abortion, pro-gun, anti-tax -- and now a Democratic congressman. Continued...