| Criteria | Districts in Category | Total Districts in Category | Assumption | Projected Democratic Victories | Projected Republican Victories | Seats Switching Democratic to Republican | ||||
| Seat currently Democratic | and | Incumbent running | and | Obama won with 60% or more | CA-36, CA-47, CT-4, MI-12, MI-13, MO-1, NM-1, NM-3, TN-9 | 9 | 100% Democratic victories, 0% Republican victories | 9 | 0 | 0 |
| Seat currently Democratic | and | Incumbent running | and | Obama won with 55-60% | CO-7, CT-2, CT-5, IL-8, IL-14, MA-10, ME-2, MI-9, NV-3, NJ-12, OH-1, PA-11, VA-11, WI-3 | 14 | 75% Democratic victories, 25% Republican victories | 10.5 | 3.5 | 3.5 |
| Seat currently Democratic | and | Incumbent running | and | Obama won with less than 55% | CA-11, FL-8, GA-12, IL-11, IN-2, IA-3, MI-7, NH-1, NJ-3, NY-1, NY-19, NY-20, NY-23, NC-8, OH-15, OR-4, OR-5, PA-8, VA-2, WI-8 | 20 | 50% Democratic victories, 50% Republican vicories | 10 | 10 | 10 |
| Seat currently Democratic | and | Incumbent running | and | McCain won | AL-2, AZ-1, AZ-5, AZ-8, CO-3, CO-4, FL-2, FL-24, ID-1, IN-9, MD-1, MS-1, NM-2, NY-29, NC-11, ND At Large, OH-16, OH-18, PA-3, PA-4, PA-10, SC-5, SD At Large, TN-17, VA-5 | 25 | 0% Democratic victories, 100% Republican victories | 0 | 25 | 25 |
| Seat currently Democratic | and | Incumbent not running | and | Obama won with 60% or more | AL-7, CA-33, FL-17, HI-1, RI-1 | 5 | 80% Democratic victories, 20% Republican victories | 4 | 1 | 1 |
| Seat currently Democratic | and | Incumbent not running | and | Obama won with 55-60% | NH-2, PA-7 | 2 | 50% Democratic victories, 50% Republican vicories | 1 | 1 | 1 |
| Seat currently Democratic | and | Incumbent not running | and | Obama won with less than 55% | KS-3, WA-3 | 2 | 25% Democratic victories, 75% Republican victories | 0.5 | 1.5 | 1.5 |
| Seat currently Democratic | and | Incumbent not running | and | McCain won | AR-1, AR-2, LA-3, TN-6, TN-8 | 5 | 0% Democratic victories, 100% Republican victories | 0 | 5 | 5 |
| Seat currently Republican | AL-3, AL-5, AK At Large, AR-3, CA-3, CA-4, CA-19, CA-26, CA-44, CA-45, CA-48, CA-50, DE At Large, FL-10, FL-12, FL-16, FL-21, FL-25, GA-9, IL-10, IL-13, IN-4, IN-5, KS-1, KS-2, KS-4, LA-2, MI-2, MI-3, MI-10, MI-11, MN-3, MN-6, MO-7, NE-2, NV-2, OH-2, OH-12, OK-5, PA-6, PA-15, SC-1, SC-2, SC-3, SC-4, TN-3, TX-10, WA-8 | 48 | 0% Democratic victories, 100% Republican victories | 0 | 48 | 0 | ||||