The House of Representatives has two "cloakrooms" - one for each party - but the humble name hides an important centre of power. C-SPAN describes them as "long, narrow L-shaped enclosed rooms at the back of the chamber. Many Members enter and leave the floor by going through their party's cloakroom, and it's the first place staff look for missing Members."
"The cloakrooms control all the action" of the parties "on the floor, including speaking time, order and organization. These rooms are closed to all except Congressmen and a few of their trusted staffers, and have their own phone numbers."
The rooms have places to sit quietly, or to talk (even to conspire!). Food and drink may be consumed. (they have snack bars (basic diner food, e.g. hot dogs, sandwiches, and soups) Most importantly they are an information hub.
The republicans use the name for their internet information hub - accessible here.
The work of the Democratic cloakroom is described by Donnald K. Anderson in the video below
C-SPAN reports "Besides Members and congressional staff, many journalists call the cloakroom for the most up-to-date information on these vital matters. Because of the overwhelming volume of calls each cloakroom has its own taped scheduled floor hot-line, updated throughout the day. Here are the numbers. All area codes are (202): House Republican,  202 225-7430. House Democratic,  202 225-7400. "