In previous posts, I explained why there is a real danger that we might see a serious attempt to "pack" the Supreme Court at some point within the next few years, and why such a development might well cause great harm, if it happened. To avert this threat, prominent legal scholar (and Volokh Conspiracy co-blogger) Jim Lindgren proposes a constitutional amendment fixing the number of Supreme Court justices at nine. I am more than happy to support this idea! If it gets enacted, it would indeed put an end to the danger, permanently plugging this loophole in our constitutional system.
But the amendment strategy has a significant potential weakness. Constitutional amendments are extremely difficult to pass. The standard pathway requires support from two-thirds of both houses of Congress and three-fourths of state legislatures. The alternative of a convention of the states also requires a large supermajority. If there are powerful political forces that want to pack the Court in the near future (or at least keep open the possibility of doing so), they can easily block the enactment of Jim's excellent proposal. And, in this case, liberal Democrats are increasingly open to the court-packing idea, even if it does not yet enjoy anything approaching consensus support on the left. They are unlikely to give it up at a time when many liberals see it as the best available countermove to what they regard as an illegitimate conservative takeover of the Court. Liberal Democrats almost certainly have the votes block the enactment of an anti-court-packing amendment in Congress, the states or (most likely) both.
Thus, such an amendment can only pass as part of a political deal in which the left gets some reciprocal concession from Republicans. For example, the membership of the Court could be temporarily expanded to ten, and the president at the time (if he is a Republican) can commit to choosing a nominee endorsed by Democratic leaders in Congress. The temporary temporary could serve for a term of, say, 18 years after which the membership of the Court would revert to nine. This could potentially split the difference between the two sides. It would give the left an extra justice, but would fall short of the two (or more) new liberal seats that progressive supporters of court-packing hope to add. Perhaps liberals would prefer one guaranteed seat in the hand to two more uncertain ones "in the bush."
One can imagine other types of concessions that could incentivize the left to support the Lindgren Amendment. The trick is to find one that would simultaneously win sufficient liberal support without alienating the right. This may not be an insuperable task. But, in this era of deep polarization, it certainly will not be easy. If it were up to me, I would be willing to go to considerable lengths to permanently eliminate the spectre of court-packing. Partisan Republicans might not be as forthcoming.