Complicating the matter further, employees may choose to work without pay, because backpay is legally required by law (certain individuals are trying to undo this, however, I lack the patience or desire to get into this on HN). That means that if employees have the means to hold out, they will ultimately be compensated.

Perhaps someone more informed can provide more detail.

The problem is getting everyone to work in such a concerted manner.

[0] The White House this week argued that the law that clearly and unambiguously requires this does not in fact do so, and OMB removed references to the law and its requirements from their shutdown guidance to agencies, so I would not count on the Administration honoring it, at least initially.