I thought it would be hidden, out in the woods, or some kind of backroom deal.
The tightly controlled choreography stirred the emotions while celebrating the unsung heroes of the backroom.
In our political system, presidents are not empowered to promise to launch wars in backroom negotiations with foreign leaders.
Having to do with political expediency; from the inner circles of party affairs: a backroom decision/ backroom motives
[1940s+;fr see what the boys in the back room will have, suggesting a secret conclave in the rear of a saloon]