But unlikely to do so when they're threatened e.g. by "someone" leaking evidence of "transgressions"... e.g. sexual encounters with affairs/prostitutes, excessive drinking, inappropriate conduct with minors, clandestine meetings with "sponsors" (aka corruption)... and Congressmen (or, politicians in general) are not exactly known for ethical behavior, which makes them all extortionable.

A lot of this kind of "searching for evidence" can already be done using existing surveillance infrastructure, I believe it was called LOVEINT after the Snowden leaks.