Complex sentence: September 11,2009 Breitbart and O'Keefe accused CNN of favoring ACORN in its coverage, but CNN had a record of having reported on ACORN related allegations of registration fraud.
Split into simpler sentences: September 11,2009 Breitbart and O'Keefe said that CNN of favoring ACORN in its coverage. But, CNN had reported on ACORN-related allegations of registration fraud.