Another factor, experts said, are the justices themselves. If the new 6-3 majority moves quickly to assert itself on divisive issues such as abortion or guns, that could galvanize support on the left for change. On the other hand, if it pumps the brakes on those controversial cases, that could make it harder for progressives to organize.

“What political science has said is that when Congress introduces bills – when there’s political pressure to reform the court – in general the court backs down,” said Joshua Braver, a University of Wisconsin law professor who has studied past campaigns to change the court. “As a matter of institutional heft, Congress has so many ways to strip its power.”…

Biden had previously said he would name progressives and conservatives to the group. But some progressives are grumbling about the names Biden is reportedly considering, including Jack Goldsmith, a Harvard Law professor who worked in the Bush administration. Goldsmith, whose name appeared as a potential pick in a recent Politico article, has drawn the ire of liberals in part for a 2018 magazine piece in which he praised conservative Kavanaugh, then a high court nominee, for his “careful, honest, detached interpretation of the Constitution.”

“The fact that someone like that is put on suggests we’re going to have some real problems; I hope I’m wrong,” said Molly Coleman, executive director of the People’s Parity Project, a group of law students and lawyers aiming to change the judiciary.