>Hmm, what about those congresspeople and other officials who can be
>proven not to have come into contact with the infections? (for
>example, a congressman inspecting one of the installations in the
>outer parts of the system or on holiday in a remore habitat). Would it
>be possible to set up some skeleton government using them, or would
>that be unconstitutional?
It is not spelled out that far in the American Constitution, but given the structure that was set up, it would be reasonable for one remaining congressperson to attempt to restore some semblance of order. Americans do prefer to have someone elected in charge.
What could also happen, in another corollary, is that each of the individual states decides to renege federal authority and secedes from the Union. If the federal government became untrustworthy enough, it would be in the best interests of the states to preserve their interests by seceding and operating on the state level of government. They don't necessarily need federal resources to keep operating on a basic level.