Senate Republicans told the Supreme Court on Thursday that they will work to prevent Democrats from expanding the size of the nine-member panel.
In an unusual letter, Senate Majority Leader Mitch McConnell and the 52 other Republican members of the Senate took issue with a friend-of-the-court brief filed earlier this month by Senate Democrats.
That brief, led by Democratic Sen. Sheldon Whitehouse of Rhode Island, warned the court that it was "not well" and urged it to "heal itself before the public demands it be 'restructured in order to reduce the influence of politics,' citing language from a recent Quinnipiac University poll.
"It's one thing for politicians to peddle these ideas in Tweets or on the stump," the Republican senators wrote. "But the Democrats' [friend-of-the-court] brief demonstrates that their court-packing plans are more than mere pandering. They are a direct, immediate threat to the independence of the judiciary and the rights of all Americans."
The Republicans characterized the brief, and in particular the plans to expand the size of the court, as a "direct, immediate threat" to the independence of the federal judiciary.
"While we remain Members of this body, the Democrats' threat to "restructure[ ]" the Court is an empty one," the senators wrote. They said they shared the view of Justice Ruth Bader Ginsburg, the senior member of the court's liberal wing, who said this year that she opposed court expansion, noting "nine seems to be a good number."
Democratic candidates for president have proposed various reforms for the top court, including expanding its size and altering the way judges are selected. South Bend, Indiana Mayor Pete Buttigieg and Sen. Elizabeth Warren of Massachusetts are among the top candidates who have said they are open to increasing the number of justices. Gillibrand, who dropped out of the presidential race on Wednesday, signed onto Whitehouse's brief.
The Democrats' brief argued that the court was in danger of being perceived as cozy with conservative organizations such at The Federalist Society, an influential legal group, and the National Rifle Association, whose members include gun owners.
In a statement on Thursday, Whitehouse said that the response to his brief "from Republicans and the partisan donor interests driving the Court's polarization shows exactly why it's time to speak out."
"They want us to shut up about their capture of the Court; we will not," the senator said.
Both the letter and Democrats' earlier brief are atypical. The Supreme Court, which seeks to portray itself as being above the partisan political fray, has found itself at the center of a divisive political struggle, particularly after the retirement of Justice Anthony Kennedy last year enabled President Donald Trump to shift the balance of the body with the appointment of Justice Brett Kavanaugh.
Chief Justice John Roberts has sought to push back on questions about the court's legitimacy as a nonpartisan legal authority. After President Donald Trump accused a federal judge in California last year of being an "Obama judge," Roberts issued a rare statement.
"We do not have Obama judges or Trump judges, Bush judges or Clinton judges," Roberts wrote at the time. "What we have is an extraordinary group of dedicated judges doing their level best to do equal right to those appearing before them. That independent judiciary is something we should all be thankful for."
The Supreme Court did not respond to a request for comment.