Complex sentence: The ad was an identical copy of a 2008 ad published by then-presidential candidate Mitt Romney, except that Ward replaced Romney's approval message at the end of the video with her own.
Split into simpler sentences: The ad was an identical copy of a 2008 ad published by then Presidential Candidate Mitt Romney. The difference between the two is that Kelli Ward replaced Mitt Romney's approval message at the end of the video with her own.