Associate Justice Ruth Bader Ginsburg, sits with fellow Supreme Court justices for a group portrait at the Supreme Court Building in Washington, Nov. 30, 2018.

Justice Ruth Bader Ginsburg says she opposes proposals by Democratic presidential candidates to increase the number of seats on the Supreme Court because doing so would make it look partisan.

"It would be that — one side saying, 'When we're in power, we're going to enlarge the number of judges, so we would have more people who would vote the way we want them to,'" Ginsburg told NPR in an interview that aired Wednesday.

"Nine seems to be a good number. It's been that way for a long time," she said Tuesday.

Several Democratic candidates have said they are open to increasing the size of the nine-justice court.

Former Texas Rep. Beto O'Rourke said shortly after entering the race that expanding the court to 15 members is an "idea we should explore." Pete Buttigieg, the mayor of South Bend, Indiana, has made court reform a centerpiece of his campaign, including the idea of court expansion. Sens. Kamala Harris, Elizabeth Warren and Kirsten Gillibrand have said they are open to the idea.

But Ginsburg, the court's most senior liberal justice, said the idea contradicts the premise of an independent judicial branch.