President Joe Biden ordered a study of adding seats to the Supreme Court, creating a bipartisan commission that will spend the next six months examining the politically incendiary issues of expanding the court and instituting term limits.

In launching the review last Friday, Biden fulfilled a campaign promise made amid pressure from activists and Democrats to realign the Supreme Court after its composition tilted sharply to the right during President Donald Trump’s term. Trump added three justices to the high court, including conservative Justice Amy Coney Barrett, who was confirmed to replace liberal Justice Ruth Bader Ginsburg just days before last year’s presidential election.

During the campaign, Biden repeatedly sidestepped questions on expanding the court. A former chair of the Senate Judiciary Committee, Biden has asserted that the system of judicial nominations is “getting out of whack,” but has not said if he supports adding seats or making other changes to the current system of lifetime appointments, such as imposing term limits. The 36-member commission, composed largely of academics, was instructed to spend 180 days studying the issues. But it was not charged with making a recommendation under the White House order that created it.

The panel will be led by Bob Bauer, who served as White House counsel for former President Barack Obama, and Cristina Rodriguez, a Yale Law School professor who served in the Office of Legal Counsel for Obama.

The makeup of the Supreme Court, always a hot-button issue, ignited again in 2016 when Democrats declared that Republicans gained an unfair advantage by blocking Obama’s nomination of Judge Merrick Garland to fill the seat left empty by the death of conservative Justice Antonin Scalia. Then-Senate Majority Leader Mitch McConnell, a Republican, refused to even hold hearings on filling the vacancy, even though it was more than six months until the next presidential election.

In the wake of McConnell’s power play, some progressives have viewed adding seats to the court or setting term limits as a way to offset the influence of any one president on its makeup. Conservatives, in turn, have denounced such ideas as “court-packing” similar to the failed effort by President Franklin D. Roosevelt in the 1930s.

Earlier this week, liberal justice Stephen Breyer, the court’s oldest member, warned liberal advocates of making big changes, including expanding the number of justices. Breyer said in a speech Tuesday that advocates should think “long and hard” about what they’re proposing. Politically driven change could diminish the trust Americans place in the court, Breyer said.

The size of the court has been set at nine members since just after the Civil War.

Any effort to alter it would be explosive, particularly at a moment when Congress is nearly evenly divided. Changing the number of justices would require congressional approval.

“With five justices appointed by presidents who lost the popular vote, it’s crucial that we consider every option for wresting back political control of the Supreme Court,” said Nan Aron, president of the Alliance for Justice, a liberal judicial advocacy group. “President Biden’s commission demonstrates a strong commitment to studying this situation and taking action.”

Biden pledged to create the commission during an October television interview. Its launch comes amid speculation as to whether he will be able to put his own stamp on the court if Breyer retires at the end of the current term.

The 82-year-old Breyer is the oldest member of the court and the senior member of its three-justice liberal wing. A number of progressive groups have urged Breyer to retire while Democrats still control the Senate and the confirmation process.

Biden has promised to appoint the first Black woman to the court.