“She has always said she is going to do this job as long as she can do it full steam,” Ms. Knizhnik said on Thursday. “But from an actuarial standpoint, she sees that there aren’t going to be too many more elections during her tenure.”

A legal advocate for most of her life, Justice Ginsburg made a name for herself when she represented the Women’s Rights Project of the American Civil Liberties Union in several landmark cases before the court on issues including gender discrimination, equal protection and due process.

After serving on the United States Court of Appeals for the District of Columbia for more than a dozen years, Justice Ginsburg was elevated to the Supreme Court by President Bill Clinton in 1993, becoming the second woman to serve there. Though a stalwart of the court’s liberal bloc, she was hardly a household name.

But that started to change in the last decade, as conservatives on the court more aggressively asserted their philosophy and Justice Ginsburg began reading fiery dissents.

In a 2007 case about discrimination in the workplace, she said the court “does not comprehend, or is indifferent to, the insidious way in which women can be victims of pay discrimination.” In 2013, she said that “only an ostrich” would believe that race would not continue to be a factor in university admissions despite the court’s ruling in an affirmative action case. In a religious liberty case the next year, Justice Ginsburg said the majority on the court had endorsed a radical overhaul of corporate rights.

Her dissent in that case, involving whether Hobby Lobby, the arts and crafts store chain, must provide insurance coverage for contraception to its employees, went viral on the internet, spawning Facebook memes and even a tribute song on YouTube. Ms. Knizhnik’s Tumblr site, Notorious R.B.G., sells T-shirts, coffee mugs, iPhone cases and tote bags with Justice Ginsburg’s face on them.

Ms. Knizhnik said the internet offered a caricature that exaggerated the liberal philosophy of Justice Ginsburg, who had formed a close personal bond with Justice Antonin Scalia, the court’s most outspoken conservative before his death this year.