If you didn't know any better, Tuesday night's jaunty, optimistic State of the Union address might convince you that the President's approval ratings were well above 50 percent and that he had a supportive Congress waiting in the wings. On the other hand, Obama could just as well have had a burr in his saddle. In all likelihood, he's governing now with as good a supporting cast as he'll have in the next one thousand days.

Barring political earthquakes, the type of which haven't been seen in 12 years, Democrats aren't likely to regain control of the House, and they might lose several seats in the Senate. No matter how successfully Obama prosecutes his agenda in 2013, this fact won't change. It explains why he will govern at a remove from Congress for the next few years, and why he was so eager to accept a two-year budget deal that many Democrats found distasteful.

Given the disastrous approval ratings of House Republicans, it's easy to wonder why Democrats aren't in better shape. But past elections heavily influence future ones. In 2010, House Republicans won more than 60 new seats, and their partisans in state legislatures set out to draw them as safely as possible for the future. That's why, in 2012, Democrats won the House popular vote by 1.4 million but managed to net only eight House seats, leaving Republicans with a healthy 33 seat cushion.

As Rhodes Cook notices, House and national presidential vote concentrations are highly synchronized, more so than at any point in nearly 60 years. Only 26 House districts chose a different party's nominee in the presidential election. Just four years earlier, almost a fifth of all Congressional districts saw a split vote. (The why: Secondary to the party's growing conservative energy, Republicans have all but consolidated control of formerly Democratic states in the South, squishing and concentrating Democratic voters into small enclaves; in the Northeast, solid Republican districts are similarly sparse.)

Gerrymandering after Congressional redistricting might help Republican members of Congress stick to their districts, but the effect of their incumbent powers, still the preferred explanation for why it is so hard to dislodge individual members of Congress, would make it difficult for Democrats to challenge the majority anyway, even if the country had yet to finish its geographic sorting. Democrats can't pick up too many Congressional seats at once because Democrats tend to "waste votes." That's not a knock. It's a fact that's plain on a map. Democratic seats are increasingly (and really, have almost always been, in the modern era), smaller, geographically, than Republican seats, and clustered around cities. The party can drive up its margin without winning new seats. Democratic voters tend to be more urban than Republican voters.

The Senate is in play because there are enough competitive Republican candidates; Democrats have a much better map in 2016.

In the last decade of the 20th century, Democrats managed to hold on to majorities in Congress far more regularly than they won the presidency. The first half of the 21st century reverses this trend: Democrats are better positioned to win the presidency than they are to effect dramatic swings in the House.

They'll have to win back Congressional districts seat by seat, which will require a lot of concentrated money and resources, superb candidates, weak opponents, and a lot of luck. The President won't be on the ballot to lift Democratic vote totals in marginal districts, and while the economy is improving, voters are not rewarding Democrats with higher approval ratings and Obama's job approval rating is above ten points below where it needs to be in order for him to generate an off-year bandwagon effect.