Everybody wants these guys to run half the government for the next decade, right? Photo: Win McNamee/2011 Getty Images

One thing you may have missed even if you’re following the election really, really closely is that Americans get to vote this November to decide control of not on one or even two but three bodies: The president, the Senate, and the House of Representatives. The relative importance of the three could be apportioned about 50:25:25. The ratio of news coverage to the race for control is about 80:19:1. Hardly any public polls exist. Every couple of weeks, the handful of Congressional handicappers update their projections, based on entrail-reading about the national mood and the cut of this or that candidate’s jib. But nobody has much of an idea what will happen in the House, and hardly anybody cares, either.

The primary reason for this is that the House is not a competitive national election. People are naturally, and increasingly, self-segregated by partisanship. On top of that, Democrats tend to bunch together in urban areas, where their votes are packed into districts with huge, wasted majorities. And on top of that, Republicans were fortunate enough to have a big wave election right before it was time to redraw the House district maps following the census, an opportunity they used to lock in their majority in many states.

The upshot is that it would take a huge wave for Democrats to win the House. The median House district is three percentage points more Republican than the country as a whole. Republicans could maintain control merely by winning their own natural territory. Democrats could only win the House by penetrating deep into red America.

There are two incredibly depressing lessons here. The first is that the incredibly important decision of which party controls the House is something we Americans have little say over. But conceding Republican control of the House means allowing all manner of extreme and unpopular policies. One is that Republican control means that the debt ceiling will become a regular game of Russian roulette with the world economy rather than a posturing opportunity, at least as long as there’s a Democrat in the White House. Another is that bipartisan agreement on the long-term budget is impossible.

These are both policies that are unpopular even with large chunks of the Republican party. In theory, voters could get angry enough to kick out the crazy Republicans driving these radical policies. In practice, nobody considers this realistic. So there’s essentially no disciplinary measure available to stop policy decisions supported only by a political fringe. Ultraconservatives control the House Republican caucus, and Republicans control the House, so nobody is even trying to change this.

Second, the political system that exists gives the Democratic Party almost no margin for error. The House is locked into the GOP for another eight years. The Senate, meanwhile, is tilted very heavily to the GOP. The Senate over-represents people who live in small states, and people who live in small states lean Republican. (That’s why George W. Bush won 30 states in 2000 even while slightly losing the popular vote.) All things being equal, Republicans will enjoy a pretty large Senate majority.

The two parties have approached this underlying fact differently. Republicans have instilled powerful discipline on their Senators, giving them almost no leeway to depart from the conservative line. In several cases, the party’s almost fanatical discipline has made it risk or throw away seats, by driving electable moderates out and nominating crazies. The upside to this strategy is that the Republicans who do win recognize that they have to toe the party line. Basically, Republicans are spending down their natural Senate majority, making their party smaller but much more disciplined.

Democrats have the opposite approach. Forced to hold Republican-leaning territory, they give their candidates wide latitude to break from the party. The upside is that this helps Democrats hold more Senate seats than they should. The downside is that many of these Senators fear identifying too closely with their party. In 2001, twelve Democrats in the Senate voted for the Bush tax cuts. Democrats appear well-poised to hold the Senate in 2012, but anybody counting on this to restrain a President Romney is probably deluded.

Imagine you’re Romney, trying to pass some version of the Ryan plan through a Senate with, say, 51 or 52 Democrats. In 2014, Democrats will be defending Senate seats in states like Alaska, Louisiana, Montana, South Dakota, and North Carolina. All those senators will be desperate to burnish their bipartisan credentials. Romney would barely sweat the task of picking off a couple of them to support his agenda, perhaps in return for some a favor to their local industry.

In practice, then, Democrats have just one election that gives them a remotely fair chance to win: the presidential election. They have no chance to control the House or to wield effective control over the Senate. The whole weight of the party’s agenda — protecting health-care reform, progressive taxation, and everything else that might be mowed down by Republican-controlled government — rests on Barack Obama’s shoulders.