When we last left the Senate races on Friday, the state of the polling was consistent with the theory that undecided voters would break for the GOP due to President Obama’s low approval ratings and the consequent surge for the GOP in the generic ballot, but we had not yet seen enough movement to conclude that this was actually going to happen. We have new polling since then in eight of the 20 “battleground” Senate races, and the story remains similar, but slightly more optimistic for Republicans in a few of the key races, notably Iowa. But we still lack good polling in Kansas, and the New Hampshire Senate race continues to look like the toughest nut to crack. I’ll also discuss the governors races below.
This is a slightly different format for the chart, which once again is drawn from the RealClearPolitics polling averages. As before, the R2% column shows the Republican’s current percentage of the two-party vote (the only metric that matters); U% is the percentage of the polled electorate that is either undecided or currently backing a minor third party candidate, but in one race, South Dakota, former Republican Senator Larry Pressler gets enough support to be included in the RCP average, so I list his support separately. “R to 50″ shows what percent of the undecided/independent vote the Republican needs to get to 50.01% of the vote and win; in South Dakota, I used 50.01% of the non-Pressler vote. The races shown in bold have new polling since September 26; in this and the governors’ races chart, I put an asterisk next to races where there’s not enough polling for RCP to compute an average. I also added an extra row at the bottom that shows that the two GOP contenders in Louisiana, Bill Cassidy and Rob Maness, need between them to capture less than a quarter of the remaining undecideds to force Mary Landrieu into a December runoff (which if the polls hold up would be against Cassidy). As you can see, if we take the polls at face value, Iowa has now slid into the column of races in which the GOP candidate, Joni Ernst, no longer needs to win even 40% of the remaining undecided voters, while Scott Brown in New Hampshire has to either …read more