The Vice-president is the Senate's presiding officer and is technically that body's highest-ranking official; the president pro tempore has the second-highest rank and has many high-profile responsibilities, including swearing in new members, opening each Senate session, maintaining oversight over floor operations, and signing bills that the Senate passes, to go the President for signing into law or to the House of Representatives if that house hadn't already approved.

Murray, who had been the Assistant Majority Leader since 2017, is the Democratic Party's second-most senior member, behind California's Dianne Feinstein, who declined to take the position. Murray is also chair of the Senate Appropriations Committee. Her previous experience includes chairing the Senate Budget Committee, the Veterans' Affair Committee, and the Health, Education, Labor and Pensions Committee.

Murray was also her home state's first female Senator, elected to the federal body in 1993. She served in the Washington State Senate from 1988 to 1992.

Before Murray, 92 men had served as the Senate's President Pro Tempore, some on multiple occasions. The longest-serving of those was William Frye (R-Maine), who was in the position from 1896 to 1911.