In October 2019, incumbent Republican Representative Greg Walden of the 2nd district announced that he would not seek a twelfth term.

[2] Incumbent Democratic attorney general Ellen Rosenblum was originally appointed to the role by former governor John Kitzhaber on June 29, 2012, to finish the term of her predecessor John Kroger, who resigned from office.

[11] Incumbent Republican secretary of state Bev Clarno was originally appointed to the role by Governor Kate Brown on March 31, 2019, to finish the term of her predecessor, Dennis Richardson, who died in office.

[12] Brown announced that she was only interested in appointing a successor to Richardson who wanted the day-to-day responsibilities of the office and would not run for election to a full term, a condition to which Clarno agreed upon her appointment.

[11] In the previous legislative session, Democrats held a majority of 18–12 in the Senate and 38–22 in the House of Representatives.