This one was found on the website The Daily Kos. The writer was discussing how Nancy Pelosi controls the various House Subcommittees. This is a nice blend of “walking a tightrope” (to do something with extreme care and precision) and “on a tight leash” (under someone’s strict control). Both phrases have the word “tight” in them and “ropes” and “leashes” are similar items. Also, both phrases entail exactness and control. Here is the link to the malaphor: https://www.dailykos.com/stories/2019/6/5/1862845/-NY-Offers-Chairman-Neal-Trump-s-Tax-Returns-Neal-Says-No-Thanks-Unbelievable
A tip of the hat to Barry Eigen who spotted this hidden creature in the word forest.