In addition to race-specific polling, Public Policy Polling (D) has released a series of polls testing what we might call the "state generic ballot." In other words, while conducting its Senate or gubernatorial polling, PPP also asked a statewide sample whether they planned on voting for the Republican or Democrat. So, for example, in Illinois, the sample reported that 44 percent would vote for the Republican, while 44 percent would vote for the Democrat.

The results for the four states are summarized in Table 1 below. I've also included the parties' statewide performances in congressional races in 2002, 2004, 2006 and 2008.

Two important notes about the table. (1) I've allocated undecideds from the PPP polls equally. So, while the Illinois result was 44-44, I've made it 50-50 in the chart. Without that, you'd have an apples-to-oranges comparison with the actual results of earlier years. Please note that this may bias results toward the Democrats, as we might expect undecideds to break against the incumbents instead of splitting equally between the parties.

(2) I've had to do some estimating in various years to account for unopposed members. This is important because if, for example, Chaka Fattah is unopposed in heavily Democratic PA-02, the state will look more Republican than it actually is. So when there are unopposed members, I've substituted the numbers from a similar district. So, if Fattah were unopposed, I would enter the numbers for politically similar PA-01 for PA-02 as well.

These results underscore what a challenging year this is shaping up to be for Democrats. In Pennsylvania, Michigan and Illinois, the numbers are the worst for Democrats all decade. The turnaround is especially severe in Illinois, where Democrats would drop from 62 percent of the statewide vote to 50 percent.

If Republicans were to return to their 2002 levels in the popular vote, they would pick up three seats in Illinois, three seats in Michigan (I assume they would pick up MI-01), four in Ohio, and five in Pennsylvania; they'd also come close in PA-13 (48 percent R in 2002) and PA-17 (49 percent R in 2002). That's a little more than a third of the seats the Republicans need to take back the House, from these four states alone. And given the assumptions that we're making, this is probably understating the strength of the Republicans position.