As Dick would say, simply put there's no doubt that the Citizens United decision heavily influenced the 2010 midterm elections.
One of the two ways of reversing course, which republicans can do nothing about, is maintaining the presidency and the Senate in 2012.
Roe vs Wade, Citizens United and many other decisions are at stake. The Senate, the body responsible for Supreme Court confirmations, is currently standing at 53-46-1.
My guess is that about 8-10 democratic Senators and 4 republican senators are unsafe. My guess is that republicans will force gridlock and try to blame the way the government never worked on the President and the Senators that survived. They are operating on a 24/7 election schedule and it is to their benefit that this mess continues.
Here are the Senators up for re-election in 2012 along with my completely unscientific perception of who's safe and who isn't:
Dianne Feinstein of California
Tom Carper of Delaware (safe)
Bill Nelson of Florida (safe)
Daniel Akaka of Hawaii (safe)
Ben Cardin of Maryland (safe)
Debbie Stabenow of Michigan (unsafe)
Amy Klobuchar of Minnesota (safe-ish)
Claire McCaskill of Missouri (unsafe)
Jon Tester of Montana (unsafe)
Ben Nelson of Nebraska (unsafe)
Bob Menendez of New Jersey (safe)
Jeff Bingaman of New Mexico (safe)
Kirsten Gillibrand of New York (safe)
Kent Conrad of North Dakota (unsafe)
Sherrod Brown of Ohio (unsafe)
Bob Casey, Jr. of Pennsylvania (unsafe)
Sheldon Whitehouse of Rhode Island (safe)
Jim Webb of Virginia (unsafe)
Maria Cantwell of Washington (safe-ish)
Joe Manchin of West Virginia (safe-ish)
Herb Kohl of Wisconsin (unsafe)
Independent incumbent elections
Joe Lieberman of Connecticut (unsafe)
Bernie Sanders of Vermont (safe)
Republican incumbent elections
Jon Kyl of Arizona (safe)
Richard Lugar of Indiana (safe)
Olympia Snowe of Maine (unsafe)
Scott Brown of Massachusetts (unsafe)
Roger Wicker of Mississippi (unsafe)
John Ensign of Nevada (unsafe)
Bob Corker of Tennessee (safe-ish)
Kay Bailey Hutchison of Texas (safe)
Orrin Hatch of Utah (safe)
John Barrasso of Wyoming (safe)