While Congress retains its inherent contempt authority and may exercise it at any time, this inherent contempt process was last used by the Senate in 1934, in a Senate investigation of airlines and the U.S. Postmaster.
To make a scared cat feel more comfortable, set up a covered cave for them to retreat to. Line it with soft bedding and partially cover the entrance so that the cat will feel safely obscured inside. In the same vein of thought, you can purchase a cat tower for the cat to lie on top of.
The first step is to confine the new cat to one room with its litter box, food, water, and a bed. Feed your current cat(s) and the newcomer on either side of the door to this room. After the 7-10 day isolation period is done, and your new cat is healthy, you can progress to the next steps.