Casino magnate Sheldon Adelson at the presidential debate between Mitt Romney and President Obama, in Denver on Oct. 3. Adelson invested millions in an effort to help elect Romney — but only after bankrolling a superPAC for former House Speaker Newt Gingrich in his anti-Romney Republican primary battle. Nicholas Kamm/AFP/Getty Images hide caption

toggle caption Nicholas Kamm/AFP/Getty Images

Karl Rove, former adviser to President George W. Bush, speaks last year in Corpus Christi, Texas. Rove is the chief fundraiser for the biggest outside spender this election season: the twin groups American Crossroads and Crossroads GPS. Michael Zamora/AP hide caption

toggle caption Michael Zamora/AP

Former Virginia Gov. Tim Kaine is joined by his wife and daughter in celebrating his Senate victory over Republican George Allen. Mike Theiler/UPI /Landov hide caption

toggle caption Mike Theiler/UPI /Landov

Karl Rove, the founder of Crossroads GPS and a former adviser to President George W. Bush, at the Republican National Convention in Tampa, Fla., on Aug. 28. Spencer Platt/Getty Images hide caption

toggle caption Spencer Platt/Getty Images

Voters participate in early voting Friday in Silver Spring, Md. Alex Wong/Getty Images hide caption

toggle caption Alex Wong/Getty Images

U.S. Sen. Sherrod Brown (right), D-Ohio, debates his Republican challenger, Ohio state Treasurer Josh Mandel, at the City Club in Cleveland on Oct. 15. Tony Dejak/AP hide caption

toggle caption Tony Dejak/AP

Former Maine Gov. Angus King, an independent candidate for the U.S. Senate, greets potential voters Oct. 1 in Bath, Maine. Joel Page/AP hide caption

toggle caption Joel Page/AP

Costumed demonstrators on Oct. 3 in Denver, before the first presidential debate. Doug Pensinger/Getty Images hide caption

toggle caption Doug Pensinger/Getty Images