Thanks to redistricting, there are fewer swing districts than ever before. The 113th Congress is argubly the most partisan ever. Nate Silver has an excellent analysis. According to him, there are only 35 swing districts. His definition is CDs that are within five percentage points of the national popular vote margin. 2012 elections had an all-time low of such districts.
Meanwhile, Cook Political Report also finds that there are also 35 pure swing districts between D+2 and R+2. That is an all-time low. There was double that amount going into 2000 elections. They also found that just 99 are considered swing districts between D+5 and R+5. That too is an all-time low. There were as much as 140 of these swing seats in 1998. Cook calculated that "If both parties hold all their 'strong' districts, Democrats would now need to win 73 percent of all 'swing' districts to achieve a majority." Swing districts as defined as between D+5 and R+5. So they need to win 73% of those 99 districts. Cook also found that the median district is currently MI-7, Tim Wahlberg, which is R+3. In this CD, Bush got 55% of the vote, while Obama got just 52% in 2008. That's a pretty conservative district. In 2010, the median district was actually WI-01, Paul Ryan, which was R+2. In 1998, it was WA-08, Republican Jennifer Dunn, which as R+1.
Based on my own analysis, there are just six Democrats in the 113th congress that will sit in districts that John McCain won: Jim Matheson, Mike McIntyre, Nick Rahall, John Barrow, Collin Peterson, and Ann Kirkpatrick. Only one Republican in the 113th congress will represent a district that John Kerry won: Mike Fitzpatrick (PA-7), where Kerry got 51% of the vote. PA-7 is D+1. Only two other Republicans have a district that is D+1 or higher: Rodney Davis (IL-13) and Gary Miller (CA-31). Kerry got 49% in IL-13 and 48% in CA-31. According to Cook, Miller's district is D+2, the highest for any sitting Republican.
Bob Dold almost won IL-10. He lost by just 2,000 votes. That CD is D+8, where Obama got 64% in 2008 and Kerry got 54% in 2004. Republican Richard Tisei almost beat Democrat John Tierney. He lost by just 3,500 votes. MA-6 is D+7. Both Obama and Kerry got 58% of the vote there. Finally, Democrat Dan Maffei barely beat incumbent Republican Ann Buerkle, 48%-44%. Buerkle is pretty conservative for this Democratic-leaning district. NY-24 is D+4. Obama got 57% here in 2008 and Kerry won with 52%.
Some Democrats in the EVEN and D+1 and D+2 districts are moderates and will be very very tough for Republicans to beat (like Jim Costa in CA-16). Others don't have enough swing voters to the point where a Republican to win (like Matt Cartwright in PA-17). However, the fact that some Republicans can win in D+2 districts and higher in a Democratic-friendly election cycle is troubling for them. In addition, many of the Democrats' wins in 2012 were fluks (like Raul Ruiz, Joe Garcia, and Kyrsten Sinema). Republicans have a lock on the HOR for the next decade. Anyone disagree?