Complex sentence: Meanwhile, he blackmails Peter Russo, a troubled congressman from Pennsylvania, into helping him undermine Walker's pick for Secretary of State, Senator Michael Kern, and eventually has him replaced with his own choice, Senator Catherine Durant.
Split into simpler sentences: Meanwhile, he blackmails Peter Russo, a troubled congressman from Pennsylvania, into helping him undermine Walker's pick for Secretary of State, Senator Michael Kern. Underwood eventually has him replaced with his own choice, Senator Catherine Durant.