Control of the House and redistricting's effect

By Joe Williams and Anthony Salvanto

It's one of the great paradoxes in American politics. Why do Americans say they hate Congress but keep re-electing most of it? Part of that answer, at least this year, is that nationally Americans are split nearly even on their preference for their House candidates; part of it is the relative lack of competitive districts. And a big part of it is redistricting, which really just keep the number of competitive districts about the same as it was before - and that isn't too many.

First, here's a look at the findings of our 2012 House model estimate:

Republicans are widely expected to keep control of the House this year, and our new model simulation confirms that finding as well. We analyzed the partisan makeup of all the districts and ran a computer simulation to see how the nation's votes would fall across all of them, and which seats might tip because of it. The answer: not many.

Short of a massive wave materializing in the final week, Democrats aren't likely to tilt the 25 seats they'd need to retake the majority. The absence of that wave, along with a relatively small number of competitive seats after redistricting, will keep the House reasonably close to its current breakdown. This table shows why:

If the national House vote is 50-50, we expect the new House to be about where it is. Democrats could lose seats, or gain one.

But if the national House vote is 51 to 49 in favor of the Democrats, they still won't gain enough seats to retake the House, they will get perhaps 205 seats, and somewhere between a four seat pickup and - less likely - up as high as 205, with a range midpoint of 201, but that is well short of the 218 needed to take control.

Here's how it works: We start with the expectation - bourn out by past history - that the competitive races are by definition more likely to swing and contribute a lot to whatever national movement we see. We know that the national House vote is just the assemblage of all the votes in all the districts - the only question is how they all move and contribute to that national total.

We next computed the partisan makeup of the new districts from county- and precinct-level past vote as it applies now within the boundaries of all the new districts. Each district is known to have a certain number of swing votes, based on that past data.

Then we use a simple probability algorithm, based on the underlying partisanship and current race competitive ratings, to allocate swing votes between the Democratic and Republican candidates in the competitive districts until we reach the total expected national vote. So the more the national vote swings toward one party or the other, the more swing votes are expected to move within the districts. We then simulate this allocation process thousands of times and report the mean - the most likely outcome - in the table.

Part II: Redistricting and Its Impact

Redistricting can sound like a wonky thing conjuring images of lines and maps, but it has a massive, practical impact on our politics and on the partisanship we see today.

The parties essentially control how the district lines are drawn in most states - that is, which voters live in which Congressional districts - so it's no surprise that when the lines were redrawn last year, many of the districts were given either a lopsided balance of Republican or Democratic voters. Very few districts, overall, are closely balanced.

And so control of the House in 2012 isn't really up for grabs - it looks like there just are not enough competitive districts for the Democrats to net more than 25 seats and challenge Republican control without a big wave election.

All told, we consider 72 percent of today's 435 congressional districts to have solid majorities of either Democrats or Republicans in them - and therefore not likely to be consistently competitive over time. (Note that this means competitive over several cycles. Some may be competitive in any given year because of particular candidates.)

In 2010 that number was... 72 percent.

Here's how it breaks down. We studied the composition of the old, pre-2012 congressional map, and the new one after redistricting. We compared how many districts used to be competitive and how many are now.

The chart below shows the partisan profiles of the districts pre and post redistricting. You'll see that a Democrats now hold slightly fewer seats that are rock-solid Democratic majority, and the GOP has a few more. Republicans controlled the process in a lot of states because they won so many Governorships and legislatures in 2010. They made gains in many states. Overall, they got 6 new districts with solidly Republican partisan profiles, as we will see below, and eight total seats that shifted the GOP's way. But the overall groundwork for competitive seats hasn't been much altered.

Within the "hash marks" where most districts can be competitive, there isn't much movement. There are about the same number of majority and marginal districts for each party outside the "solid" category. Over time, these are the districts that have the best shot of someday hosting competitive races.

You'll see that the net change in solid majority districts is hardly much: it is 315 (154+161) either very Dem or Rep out of 435, or 72 percent, and was the same percent, 313/435 or 72 percent in 2010.

(We calculated the partisan voting behavior of voters in the new districts using past vote from an assortment of races, once the new lines were known. To be considered solidly for each party, a district has a large majorities of partisans beyond 55 percent; then we break out districts with a majority of 52 to 55 percent, and those of slight edge partisan of just a point or two to either side of 50 percent.)

Next, let's breakdown what happened and where.

The GOP won scores of state legislatures in crucial states, in the 2010 wave election. Democrats lost the governorship and states House in Michigan, Ohio and Pennsylvania, and Republicans will look to parlay the new lines there into important gains in 2012.

But much of what Republicans did with their power was, if anything, to shore up a lot of the gains they made in 2010's elections, drawing lines for newly-elected Republican members that made their new districts a little more Republican when they could. Instead of overreaching for more seats that would have been hard to defend in future elections, marginal, newly elected freshmen members benefited from revised boundaries.

A good example of this is in North Carolina. Republicans were able to win both chambers of the state legislature in 2010. Accordingly, they controlled the process in a state that doesn't give the governor, (in this case, a Democrat, Beverly Perdue) veto power. As the Republicans were a numerical majority in the delegation, they were able to dramatically alter the equation. One Democrat, Brad Miller, retired, conceding the 13th district to the Republicans, and three other Democratic seats may well be lost in November. Republicans also made potentially marginal incumbents safer in states such as Wisconsin, Tennessee, Virginia and Indiana, while Democrats shored up vulnerable members in Kentucky and Rhode Island (where they could still lose a seat.)

There is, however, an interesting twist to this story and it comes from the west coast. In a few states - notably, California - the parties don't control the process but rather it is done by an independent panel. And California is about to see its most competitive slate of races in many years.

On top of that, California held what's called the "jungle primary" which allowed the to p two vote-getters in the primaries to go on to the General election even if they were from the same party.

Democrats are favored to win new districts in Riverside and Los Angeles counties, and could easily pick up seats in San Diego, another one in Los Angeles, the Central Valley and the Sacramento area. The Republicans will likely gain another Central Valley seat, and seem to a chance to unseat two Democratic incumbents. Overall, Democrats should gain at least two seats and as many as five.

In some states, Democrats who drew the lines made life a little harder for some Republicans, which offset some of the states where the GOP made striking gains. In Illinois the close victory of Democratic Governor Pat Quinn may have been, to Democrats, the most important victory of the year. Combined with control of the state legislature, Democrats survived a legal challenge, and not only forced two Republicans into a primary, won by freshman Adam Kinzinger, but also put Joe Walsh into a tough fight. Three other Republican incumbents, Robert Dold, Judy Biggert and Bobby Schilling also face tough reelection challenges.

If we look at this in terms of states and competitiveness, there is a very slight edge to Republicans on a state-by-state basis.

• 11 states changed their maps such that the Democrats are better off, in terms of the number of districts they have at least a chance to win.

• 14 states changed their maps such that the Republicans are better off, in terms of the number of districts they have at least a chance to win.

• 25 states changed their maps such that niether party became better off in the number of districts they have a chance to win.

Overall, just from the initial re-allocation of seats following the 2010 census, it was clear the shift was headed toward more Republican states. When Texas gained four districts, Florida two, and Utah, Arizona, Nevada, Washington, South Carolina and Georgia one each, it was clear that the Republicans started out off with a distinct advantage. New York and Ohio lost two apiece, plus a one-seat loss for Pennsylvania, Michigan, Illinois, Massachusetts, Iowa, Louisiana, New Jersey and Missouri. Just in terms of the 2008 presidential election that was won by a Democrat, Barack Obama, the Republicans would have gained four electoral votes, not including Florida and Ohio, which are hardly Democratic bastions.

But the real impact of all this will likely be felt beyond 2012, as demographic changes and population movements take hold. The impact of future demography may endanger Republicans in states such as Texas and California that seem safer right now. Since there appears to be no wave in the present electoral environment, it appears as if the impact of congressional redistricting is likely to play out over future elections... and legal challenges.