As the 2006 midterm elections approached, pollsters, scholars, and
journalists attempted to predict whether the Democrats would take
back the House, Senate, or both. Much media attention was paid to
President George W. Bush's declining popularity and the public's
dissatisfaction with the Republican-controlled Congress (see e.g.,
Cook 2006). With most attention paid to
the immediate political dynamics of the campaign, less noticed
(though not entirely neglected) was the fact that the Democrats
faced a significant structural disadvantage in their effort to
retake both houses of Congress. The Democrats faced an uphill battle
to control the Senate simply due to the small number of seats that
were seriously contested. Their hurdle to taking over the House was
subtler but perhaps just as high: as we show here, they needed to
win well over half the vote share in order to have an even chance of
winning 50% of the seats, thereby overcoming a structural advantage
enjoyed by Republicans leading up to Election Day.We thank Gary Jacobson and Walt Borges for
generously sharing their data, Robert Erikson, Eduardo Leoni,
Robert Shapiro, David Epstein, and two anonymous reviewers for
helpful comments, and the National Science Foundation for
financial support. Replication datasets and statistical code are
available at
www.columbia.edu/∼jpk2004/house2006.html.