Rebuilding the JCPOA will require skillful diplomacy with Iran, the other parties to the deal, and Congress. It may not be possible. If it is possible, however, it cannot be done by ignoring or whitewashing the JCPOA’s flaws. The Biden administration should start with Congress. It should help to establish and offer to work with a congressional observer group, composed of supporters and opponents of the deal, to address their most pressing concerns. It should promise that, after rejoining the JCPOA, the United States will work from the inside to correct the JCPOA’s flaws (and there are provisions within the agreement for doing so).