Incumbent Kate Brown took office when fellow Democrat John Kitzhaber resigned on February 18, 2015.

[5] Almost 20 Republican Party candidates ran for the office, including two previous nominees for governor in 1998 and 2016,[6][7] as well as 15 Democrats and some non-affiliates/third-party members.

[9] The next day, former House Minority Leader Christine Drazan was determined to have won the Republican primary.

[10] Notably, the general election featured three prominent female candidates, including former state senator Betsy Johnson, who was a moderate Democrat, running as an independent.

Oregon was considered a possible Republican pickup, as Kate Brown had the lowest approval rating of any governor in the United States at the time and Johnson could have siphoned votes from Kotek.