In a nationwide argument over third party spending in the midterm election campaign, Colorado is ground zero.
Negative TV ads are almost inescapable in the Rocky Mountain state, where there's an open senate seat and a tight governor's race. Many of the ads are produced by third party groups that do not have to disclose their donors.
Watch "World News with Diane Sawyer" for more on this story tonight on ABC.
Since the beginning of September, independent groups reported spending some $9.4...Full Story