In politics, the cover-up is worse than the crime. Alex Sink may have been easily forgiven if she simply said, "we screwed up, but lying about cheating in the debate is really going to damage her support. She will be seen as a political hack and a dishonest politician.
Republican Rick Scott already had a lead in the tight campaign, but look for lead to significantly widen before next week's election.
Here from the Lid are links to all three video clips which tell the story.