The exit poll consortium and pollsters: The exit poll consortium put money into improving the way it interviews voters and how it tabulates them. Their exit polls (waves 2 and 3) were accurate and insightful. Pollsters also generally acquitted themselves well. All the technological changes make it hard to survey, but pollsters are keeping up.
The Obama coalition: With Latino and young voter turnout keeping and maybe even increasing their percentages over 2008, the president has built a durable foundation and has provided a roadmap for Democrats in the future. But the coalition also must include a sufficient number of working-class white voters, and Obama's firewall strategy provided them.
Pundits: Their projections were on target, too.
Jim Messina's strategy: As he described it to me and others more than a year ago, it has held up. (1) Actively disqualify Mitt Romney as a plutocrat who is out of touch with voters and doesn't understand their concerns. (2) Microtarget and harass the hell out of the 2008 Obama coalition. (3) Use the auto bailout to build a firewall in Ohio, Michigan, Wisconsin, and Iowa. (4) Capitalize on the president's personal characteristics. National Journal's Ron Brownstein calls this the coalition of the ascendent.
Partisanship: A fired-up base helped keep Republicans in control of the House and elect Elizabeth Warren (even though her opponent, incumbent Scott Brown, had a 59 percent approval vote.)
The Republican hard line on immigration. It killed them.
Misleading ads: In Ohio, Romney was hammered by state and local press for his dishonest ads about Obama and outsourcing jobs, and even earned rebukes from auto companies.
"The War on Women." It cost Republicans the chance to take control of the Senate. Also, the Tea Party, for forcing GOPers to select unworthy candidates for office. Women turned out in greater numbers than men, and they turned out in greater numbers for Obama.
The GOP primary season: It helped to make a solid candidate unelectable by making the party almost unbelievable.
Karl Rove/Citizens United: Well, a lot of Republican political consultants got richer. But the GOP barely made a dent in the Senate, and the down-ballot races seemed not to be impacted at all. Money talked, but it didn't walk that far.