Supreme Court Justice Ruth Bader Ginsburg has repeatedly said she will retire when she is no longer able to work “full steam” — a promise that could be put to the test this week — or soon after — with the 85-year-old justice sitting out oral arguments while recovering from cancer surgery.

Ginsburg’s absence for the past three days and recent health issues have fueled speculation about her future on the high court. If Ginsburg steps down as one of the four liberal justices currently serving, President Trump will almost certainly appoint a conservative replacement, tilting the court further to the Right.

If Ginsburg is serious about her repeated vow to step down if she is not fully robust, liberals could be facing a crisis in the judiciary sooner than they think. Widely viewed as tenaciously willing to hang on with a Republican in the presidency, Ginsburg's own affirmations suggest she may view competency to conduct the court's business as a matter that rivals the court's ideological makeup in importance.

Although Ginsburg said last summer that she hopes to serve until she is 90, she has been consistent about when it will be time for her to hang up the robe: "I said I will do this job as long as I can do it full steam,” she said on Dec. 17 at the New York City premier of “On the Basis of Sex,” a movie based on her early career. Five days later, Ginsburg underwent surgery to remove early-stage cancerous nodules and was hospitalized for several days.

Last February, Ginsburg used the same phrase during an event at the Adas Israel Congregation in Washington, D.C. “As long as I can do the job full steam, I will be here,” she said.

"I will retire when it's time," Ginsburg told NPR's Nina Totenberg in 2016. "And when is it time? When I can't do the job full steam.” She used the same "full steam" phrase on at least two other occasions.

Ginsburg has faced multiple recent health issues, including cancer surgery last month and a fall in November that resulted in three fractured ribs. She previously survived two forms of cancer in 1999 and 2009, as well as heart surgery in 2014.

Despite these health challenges, Ginsburg had never missed a high court argument in her 25 years on the bench until this week. The justice, known affectionately to admirers as the “Notorious RBG,” was absent from oral arguments, and Chief Justice John Roberts said she would be participating in the case “on the basis of the written briefs and the oral argument transcript.” A court spokesperson did not respond to an inquiry about Ginsburg’s recovery status, and has given no indication of when she will return.

Although it is not unprecedented for a justice to miss arguments, it is rare. The late Chief Justice William Rehnquist missed oral arguments in a reported 44 cases in 2004 while recovering from cancer surgery. He passed away in 2005.

Ginsburg said last July that she hoped to stay on the Supreme Court until age 90, following the path of her former colleague Justice John Paul Stevens. Last year Ginsburg also hired law clerks through 2020, indicating that she had no plans to step down before then.