Republican strategist Karl Rove's Crossroads GPS group is planning to spend at least $23 million in key Senate races in the final two months of the campaign. The group is a tax-exempt non-profit and is allowed to keep the names of its donors secret. Rich Pedroncelli/AP hide caption

itoggle caption Rich Pedroncelli/AP

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

itoggle caption Doug Pensinger/Getty Images