2010 was always going to be a Republican year, in the midterm tradition. It has simply been a question of degree. Several scenarios were possible, depending in large measure on whether, or how quickly, the deeply troubled American economy recovered from the Great Recession. Had Democratic hopes on economic revitalization materialized, it is easy to see how the party could have used its superior financial resources, combined with the tendency of Republicans in some districts and states to nominate ideological fringe candidates, to keep losses to the low 30s in the House and a handful in the Senate.
Given what we can see at this moment, Republicans have a good chance to win the House by picking up as many as 47 seats, net. This is a "net" number since the GOP will probably lose several of its own congressional districts in Delaware, Hawaii, and Louisiana. This estimate, which may be raised or lowered by Election Day, is based on a careful district-by-district analysis, plus electoral modeling based on trends in President Obama's Gallup job approval rating and the Democratic-versus-Republican congressional generic ballot (discussed later in this essay). If anything, we have been conservative in estimating the probable GOP House gains, if the election were being held today.
In the Senate, we now believe the GOP will do a bit better than our long-time prediction of +7 seats. Republicans have an outside shot at winning full control (+10), but are more likely to end up with +8 (or maybe +9, at which point it will be interesting to see how senators such as Joseph Lieberman of Connecticut, Ben Nelson of Nebraska, and others react). GOP leaders themselves did not believe such a result was truly possible just a few months ago. If the Republican wave on November 2 is as large as some polls are suggesting it may be, then the surprise on election night could be a full GOP takeover. Since World War II, the House of Representatives has flipped parties on six occasions (1946, 1948, 1952, 1954, 1994, and 2006). Every time, the Senate flipped too, even when it had not been predicted to do so. These few examples do not create an iron law of politics, but they do suggest an electoral tendency.
It is however not predicted at this point that Ohio's gubernatorial race will change parties...