Congresspeople? Members of congress? Persons what are elected to work in that big domey building?

Congresspeople?

https://www.google.com/search?q=congresspeople&ie=utf-8&oe=u...

Members of Congress, or MC [1]. The UK (and other parliamentary governmental) analogue is MP -- Member of Parliament. The term fell out of favor in the US, but nonetheless exists.

[1] https://en.oxforddictionaries.com/definition/mc