Both the U.S. Senate and House elect majority and minority whips who are responsible for taking party member attendance and counting votes. Also known as assistant party leaders, whips occasionally stand in for party leaders when they are absent. At times whips round up party members for votes.
The term "whip" is derived from the fox-hunting phrase "whipper-in," which described the hunting team member in charge of preventing the dogs from wandering away during a fox chase. The first Senate whips were appointed in the early 1900s along with party leaders.
On a regular basis, whips assist floor leaders and ensure party members are in attendance during particular votes. They do this by asking their staffers to call the staffers of other party members and query as to how they plan to vote. Their staffers then enter this information into a spreadsheet.
When votes appear to be close, the whip visits party members who are on the fence and attempt to resolve their concerns or offer to help with passage of a bill the given party member is in favor of in return for the desired vote.
The day prior to the vote, the whip designates a team to poll party members one more time regarding their intended voting decisions.