Frank Underwood used an unsigned editorial from the Register's September 1978 issue which had some offensive material regarding the State of Israel against Kern. Although Kern's classmate Roy Kapeniak actually wrote the editorial (which Underwood knows), the negative media attention causes Kern to rescind his nomination. He is then replaced by Catherine Durant, Underwood's preferred choice.
Almost two years later, Underwood, now Vice President, talked to Kern regarding the upcoming impeachment vote against President Garrett Walker. He made a deal with the Senator to vote to impeach the President and get others to, in return for the post of Treasury Secretary in Underwood's administration. Kern led a bi-partisan action along with Republican senators Hector Mendoza and Curtis Haas against President Walker.
While presumably still serving as Secretary of the Treasury within the new Underwood administration, Kern was forced to resign among other members of the cabinet after Claire accused them of undermining her presidency.