I'm assuming that you are referring to the Democrats on the Senate Intelligence Committee.
The report is based on the review of millions of the CIA's own internal documents and is backed up by 38,000 footnotes.
What are the statements made by the multiple CIA Directors and assistant directors (which you believe) backed up by?
Nothing. It's just rhetoric.
What you seem to forget is that the Senate Intelligence Committee’s investigation into the CIA’s detention and interrogation program only began after it came to light that the CIA had destroyed video tapes showing their use of abusive interrogation techniques.
After discovering that their own internal documents showed detention conditions and interrogations far worse than what the CIA had previously described, the Senate Intelligence Committee authorized the review of the CIA's tactics by an overwhelming and bipartisan 14-1 vote.
And in December of 2012, the Committee approved the release of the 6700 page report by a 9-6 bipartisan vote.
So it seems that Republicans were for this report, before they were against it.