Against the background of impeachment, heightened tensions with Iran, and the Iowa Caucuses, Astead Herndon of The New York Times and Clare Malone of FiveThirtyEight join Politics with Amy Walter to provide an update on the state of the Democratic Primary.

Plus, Thanassis Cambanis of the Century Foundation analyzes the future of the US-Iran relationship in light of the assassination of Qasem Soleimani and Andrew Clevenger of CQ Roll Call provides context about the War Powers Resolution.