<Li> Kathrine Herzer as Alison McCord, Elizabeth and Henry's younger daughter . Alison planned to attend Rafferty College to pursue her dreams of fashion and design, but later changed her mind . </Li> <Li> Evan Roe as Jason McCord, Elizabeth and Henry's teenage son, a self - proclaimed anarchist . Jason is very critical of political systems in general, however in season 1 he was expelled from his school for punching a student who insulted Elizabeth . </Li> <Li> Keith Carradine as Conrad Dalton (season 2--present; recurring season 1), the President of the United States . Before going into politics, Conrad was the Director of the Central Intelligence Agency during Elizabeth's time at the CIA . In "Unity Node", he reveals that he served in the United States Marine Corps as a second lieutenant during the Vietnam War . In the third season, Dalton secures reelection as an independent after failing to secure his party's nomination, partly due to a controversial change in policy championed by Elizabeth McCord . He offers Elizabeth the role of Vice President during his campaign, but eventually names someone else in order to further his campaign . Elizabeth remains Secretary of State . </Li> <Li> Sebastian Arcelus as Jay Whitman, Elizabeth's current chief of staff and previous senior policy advisor (season 3--present; recurring season 1--2). In season 3, it is revealed that Jay's busy schedule working for the Secretary has strained his marriage . He is currently separated from his wife Abby, who maintains custody of their daughter Chloe . Jay is promoted to chief of staff in season 4 . </Li>

Who plays the acting president on madam secretary