A good read from Isaac Wood. Note the point he makes below that wave elections tend to happen in midterm, not presidential elections. This is almost certainly due to the fact that turnout in these elections tend to be slanted more towards the president's opponents.
While the midterm meltdown by Democrats was undoubtedly a severe setback—leaving them in need of a 25-seat gain to capture the House majority—it set them on firmer footing heading into 2012. Simply put, it will be very difficult for Republicans to find new Democratic seats to contest since their 2010 gains grabbed most of the districts they could easily flip. Conversely, Democrats now find themselves in the same position as the GOP was in two years ago, with a short list of districts to defend and a long list of potential targets. Republicans are at a high watermark in House seats—their current caucus of 242 members is their largest since 1949—and many of those new congressmen hail from districts where Democrats can wage a competitive contest.
The key difference between 2010 and 2012 is obvious: 2012 will be a presidential, not a midterm, election year. Although that fact may seem self-evident, it offers a litany of historical comparisons that can offer early clues as to what 2012 has in store at the House level. Over the past half-century, presidents who were reelected swept in on their coattails an average of 10 new House members of their same party. In fact, all four of the presidents who sought and won reelection since 1960 (Richard Nixon in 1972, Ronald Reagan in 1984, Bill Clinton in 1996, and George W. Bush in 2004) also picked up seats in the House. These gains ranged from 15 new House seats for Republicans in 1984 to just 3 new seats for the GOP in 2004.
If Obama wins reelection next November, history therefore suggests his party will gain a handful of House seats. There are fewer historical precedents in recent years for defeated presidents, with only Jimmy Carter’s defeat in 1980 and George H. W. Bush’s 1992 loss as potential analogies to a 2012 Obama ouster. While Carter’s loss was accompanied by Democrats surrendering 33 seats in the House, Republicans actually picked up 10 new House seats even as Bush was defeated at the top of their ticket.
Whatever the result of the presidential race, there is one constant that should be sobering for Democrats chomping at the bit to recapture the House majority. Over the 13 presidential elections of the past 50 years, only twice has either party registered a net gain of 25 or more House seats, the threshold Democrats must cross to regain control of the chamber. At least for the past half-century, the true wave elections have come in midterm years (2010, 2006, 1994, 1974, 1966) while the presidential years have seen calmer seas.