As I understand it, and I'm happy to be corrected and/or schooled in this; is that Donny has made his (populist) statement betting that :-
i) The senate 'll vote against the release.
ii) If this doesn't happen; he'll 'invoke' the -We can't release the files, as there's an active DoJ investigation, preventing 'us' from doing so- argument.
Happy to have the above picked to shreds.