Following the death of Senator John McCain, on August 25, Arizona Governor Doug Ducey will appoint a successor to take McCain’s place in the Senate, until a special election is held, in 2020. Whoever wins that election will then carry out the rest of McCain’s term, which ends in 2022.

Ducey’s choice is a big one, with implications for the state of Arizona, the makeup of the Senate, and the identity of the Republican Party. Will the appointee stick to McCain’s more pragmatic brand of conservatism, or embrace Trump’s narcissistic nationalism? Ducey has said he won’t make any announcement about McCain’s successor until after the late senator’s burial, on Sunday, but a handful of names have been reported as being contenders, including former Arizona senator Jon Kyl; former Arizona House members John Shadegg and Matt Salmon; the governor’s chief of staff, Kirk Adams; former Arizona gubernatorial candidate Barbara Barrett; and Cindy McCain — John McCain’s wife for the past 38 years.

If Cindy McCain, 64, is appointed, she will join the ranks of 47 women before her who have taken up their late husbands’ seats in Congress in a tradition known as “widow’s succession,” a practice that dates back to the 1920s in the United States.

What is a “widow’s succession”?

Also called the “widow’s mandate,” the term “widow’s succession” refers to a woman taking the place of her husband in a governmental body following his death. Historically, these women have either been appointed or have won a special election. The first woman in the U.S. to take her late husband’s place in Congress was Mae Ella Nolan, who joined the House in 1923 as a representative from California.

“Early on, that was the path that many women took to office,” Debbie Walsh, director of Center for American Women and Politics at Rutgers University, tells Teen Vogue. While the tenure for some of these women was only a year or two, others went onto long and influential careers in politics.

Margaret Chase Smith, for example, took her husband’s seat in the House following his death, in 1940, and went on to win four more terms in the House and then four in the Senate; in 1964, she became the first woman to have her name put forth for a presidential nomination at a major political party’s convention. Edith Nourse Rogers, who took her husband’s seat in 1925, after his death, also used her initial appointment to kickstart an enduring political career, serving in the House for 35 years and helping draft the G.I. Bill.

For political parties, putting forth a politician’s spouse as a replacement was thought to be the smoothest way possible to transition following a death. The logic was that it would eliminate arguments within the party over the successor, and many believed the widow would follow her husband’s particular ideology and see through his legacy.

“People elected this man to hold office for his beliefs, and the assumption was that the wife would hold those same beliefs,” Walsh says.

A 2014 Washington Post analysis of voting records found that these widows do, in fact, tend to vote along similar lines as their husbands — if anything, they tend to be ever-so-slightly more liberal. The report also points out that the time of greatest ideological differences between spouses was in the 1920s and ’30s.

Walsh says that as far as she knows, there haven’t yet been cases in the U.S. of a “widower’s succession” — a man taking over his deceased wife's seat, that is.

How common is the practice today?

Getting a seat in Congress by way of widow’s succession peaked in the mid-20th century, according to the Post. There is currently only one woman in Congress who originally inherited her seat after her husband’s death: Doris Matsui. She has represented California in the House since 2005, after taking over her husband’s seat and then winning a special election that year.